Trying to understand pattern

I just started knitting and can do some basics like cast on, knit, purl, stockinette stitch, garter stitch and cast off. So I found a pattern for a hooded dog sweater and need to make it for a large dog but I’m having some difficulty understanding the pattern instructions. I followed the instructions listed under “steps” but I don’t know what section of the sweater that it’s for and I don’t know what to do next. I pasted the full instructions below. Thank you in advance for any help. Hoping to complete this sweater for our fur baby before Christmas.

S (M-L-XL)
To fit dog chest measurement: 10 (13-16-24) ins
[25.5 (33-40.5-61) cm].
Bernat® Super Value
(Solids: 197 g/7 oz) (389 m/426 yds)
1 (1-1-2) ball(s) of #53044 (True Grey).
OR Ombres (251 m/275 yds) /
Twists (280 m/307 yds): 142 g/5 oz
1 (1-2-2) ball(s)

Size 5 mm (U.S. 8) knitting needles. Size 4 mm (U.S. 6) circular knitting needle 36 ins [90 cm] long or size needed to obtain gauge. Set of four size 4 mm (U.S. 6) doublepointed knitting needles.
18 sts and 24 rows = 4 ins [10 cm] in stocking st with larger needles.

The instructions are written for smallest size. Larger sizes follow in ( ).
With larger needles, cast on 40 (46-58-82) sts. Knit 5 rows, inc 4 sts evenly across last row. 44 (50-62-86) sts. Proceed in stocking st, inc 1 st at each end of needle on 3rd and every row to 50 (60-72-104) sts, then on following alt rows to 54 (68- 82-122) sts. Purl 1 row.

Leg Openings: Next row: (RS). K5 (5-7-11). Cast off 4 (6- 6-10) sts. K36 (46-56-80) (including st on needle after cast off). Cast off 4 (6-6-10) sts. Knit to end of row.

Note: All Leg sections are worked at the same time using separate balls of yarn for each section.
Beg with a purl row, work 1 (1½-1½-2½) ins [2.5 (4-4-6) cm] in stocking st, ending with purl row.
Joining row: K5 (5-7-11). Cast on 4 (6-6-10) sts. K36 (46- 56-80). Cast on 4 (6-6-10) sts. Knit to end of row. 54 (68- 82-122) sts.
Cont even until work after neckband measures 5 (6½-8-11) ins [12.5 (16.5-20.5-28) cm], ending with purl row. Place marker at each end of last row.

Back shaping: Cast off 6 (7-9-13) sts beg next 2 rows. 42 (54-64-96) sts.
Next row: (RS). Sl1. K1. psso. Knit to last 2 sts. K2tog.
Next row: Purl. Rep last 2 rows to 26 (36- 42-66) sts.
Cont even until work after neckband measures 10 (12½-15½- 21) ins [25.5 (32-39.5-53.5) cm], ending with purl row.
Leave sts on a spare needle.

Hood: Place markers along cast on edge on 6th (7th-9th- 10th) st from each edge. (RS). Pick up and knit 29 (33-41-63) sts between markers along cast on edge. Purl 1 row.
Next row: (RS). K14 (16-20-31). M1. K1 (place marker on center st). M1. Knit to end of row. Next row: K3. Purl to last 3 sts. K3.
Next row: Knit to center marked st. M1. Knit marked st. M1. Knit to end of row. Rep last 2 rows 4 (5-7-9) times more.
39 (45-57-83) sts. Cont even until hood measures 5 (5½-6½- 7½) ins [12.5 (14-16.5-19) cm], ending with a purl row. Cast off. Fold cast off edge in half and sew hood seam.

Back Ribbing: (RS). With circular needle pick up and knit 33 (37-51-67) sts along body from marker to back. K26 (36- 42-66) from spare needle, dec 1 st at center. Pick up and knit 33 (37-51-67) sts along opposite side of body to marker.
91 (109-141-197) sts. Do not join in rnd. Knit 8 rows. Cast off. Sew neck and belly seam.

Leg Edging: (RS). With double-pointed needles, pick up and knit 23 (29-32-38) sts around leg opening. Divide sts evenly on 3 needles. Join in rnd, placing a marker on first st. Work 8 rnds in garter st. Cast off.

See the numbers in parentheses? Those are the number of stitches for each size. Do yourself a favor and highlight the size-large instructions, which will be the middle ones in the parentheses.
You’ll cast on 58 stitches and work five rows of garter stitch for what looks to me like the neck edge, then increase four stitches evenly across the row–don’t stress about it, just scatter four increases across the row so they’re not all in one spot. At the end of the row, you’ll have 62 stitches. That’s what the (62) at the end of that row’s instructions means.
From there, you knit down until you make the openings for the front legs. Those are worked at the same time, so you’ll need separate balls of yarn for the parts that are on the chest and the part that is on the dog’s back.
After the legs, you’ll work eight inches, mark the end of that row (because it’s right about where the dog’s hind legs will need room to move) and start the decreases until the whole thing, from the neckband down, measures 15 1/2 inches, then you do the finish work.

Thank you! I guess this is not something I should try for my first project? I don’t know what it means to “knit down until I make the openings for the front legs”. I’ll read up some on the knitting code language to see if I can gain some understanding enough to get from start to finish. I’d really like to learn so that my puppy dog can have a nice and warm sweater one day.

It is kind of a complicated pattern, and you might be able to find a similar one that’s a little more simply written.

Most dog sweaters start with a collar. That’s what the garter stitch rows on that pattern are. The next part gets a little wider every row to cover the dog’s neck and shoulders.
Eventually, you have to deal with where their front legs are. the best way to get the sweater to stay on the dog (unlike a blanket, which tends to come off since they bounce around more than horses do) is to put openings or even sleeves on the sweater.
Some patterns just have open spots so the legs can go through. This one happens to have sleeves. You deal with those as the pattern says, then, just as you would with a person’s sweater, you go on knitting the flat piece that will reach from the dog’s armpits to waist. There’s an edging to deal with then, and the hood to put on.

This one has a whole lot of explanation attached:
(It might not come through if you’re not on Ravelry.)

This one should be available to you, and it’s really well explained:

Don’t give up. Just understand that one of these days all the terminology will be second nature. It’s not right now, and that’s okay. You’ll get it!