Beginner knitting tank top

Hi all,
I’m doing my first clothing knitting project and have gotten to the point of the armholes and am terribly confused on what the pattern is saying. I’m to the point where it’s highlighted in blue in the image

So this part is the decorative edge of garter stitch under the arm. You will co tinue in stocking stitch as you’ve been doing until you get to the 10 stitches under the arm (you have a marker in the centre so should be able to stop 5 stitches before the marker to begin your garter stitch if you are working the smallest size, or adjust number for your size).
When you start the garter ridges it can seem strange as the first round is knit which is also stocking stitch but on the next round of garter it is purl on these 10 stitches and that produces one ridge.
Do another 2 rounds like this to produce another ridge.

So mainly stocking stitch but with a section of 2 ridges garter under each arm.

On the next round you bind of 3 stitches (for smallest size, adjust for your size) this will be under the arm, work stocking stutch to the other arm hole and bind off 6, work across in stockingnstitch back to the first arm and bind off 3 (this arm hole already had 3 bound off). This separates front and back and you will no longer work in the round.

Does this help?

I suggest a stretchy bind off under the arm to prevent it being tight. The Icelandic bind off is my favorite, or if you don’t know it and don’t want a new thing to learn then I suggest using a larger needle size just for the bind off stitches it will help keep the arm hole flexible.

Hope this helps.
If it is not clear please say so.

Hi thanks for the info! With stocking stitch isn’t it 1 knit around the round and 1 purl around the round which is what I have been doing so the ridge would be the same pattern and not look any different? Sorry for the confusion!

In the round stocking stitch is knit every round a you are always looks at the right side which is all knits.
Flat knitting stocking stitch is knit a row purl a row.

In the round garter stitch is knit a round purl a round creating knits and purl bumps, when positioned together they form a ridge.
Flat knitting garter is knit every row which produces knits and purl on the right side of the work.

It is a bit confusing especially when you start a garter on stocking stitch because they are both knit initially but on the second round or row one of them changes.
Another confusion is you are working in the round but are soon changing to working flat which changes the way you knit.