5 Hour Baby Sweater

Hi,
I’m a beginner in knitting so please don’t laugh if my questions seems really dumb:) I’m doing a sweater pattern I found and have made it all the way until this:
**Now is the time to divide things up If you prefer it put each section on a separate length of spare yarn - I don’t usually bother if I am knitting the sleeves first. BUT if you want to make this totally seamless, see the note at the end.

Sleeve: Slip sts from first (front) section up to marker (should be 22 sts) on to right hand needle.
Cast on 2 sts, knit across sleeve section (27 sts), turn and cast on 2 sts, purl back.
Continue to work in stockinette st for 22 rows.
Next row: K2, (K2 tog, K3) 5 times, K2tog K2. Knit 7 rows. Cast off.

So my question is this:After slipping the sts to my right needle, how do I cast on 2 sts and what does it mean to knit across sleeve section? When I slip the sts to my right needle, my yarn is on the bottom so how would I continue knitting. I’m so lost and like I said I’m a beginner so I have no idea what to do. I really want to finish this for my baby:)

You should knit across the sts from the first front section, then put them on a holder. Cast on by moving the R needle to your L hand and do a knit CO, then put the needle back to the R and knit across the sleeve sts. Then turn and cast on 2 more sts and purl across them, and continue on with the sleeves.