Help with sweater pattern

This is my first sweater, and I’m stuck on the first row. Here is the pattern instruction for it:

Row 1 (RS) K1 (garter-st selvage), work 7 sts broken rib, [15 sts small double cable, 11 sts broken rib] twice, 27 sts large double cable, [11 sts broken rib, 15 sts small double cable] twice, 7 sts broken rib, k1 (garter-st selvage). Cont in pats as established until piece measures 20 (21, 22)"/50.5 (53.5, 56)cm from beg.

How do you do the garter-st selvage? And when it says work 7sts in broken rib, does that mean k1,p1,k1,p1,k1,p1,k1? I would greatly appreciate it if you could help me with this. Thanks:)

It’s just telling you that the first and last sts are knit on both the RS and WS to make the garter stitch selvedge. Don’t do anything except follow the pattern.

The broken rib pattern should be explained somewhere in the pattern notes, you probably k1 p1 on the RS and knit or purl all on the WS. Or however it’s written.

Thanks! It says that the rib stitch pattern is:
Row 1 (RS) Knit
Row 2 P1, *K1, pl, repeat from * to end

The thing I’m confused about is what to do after i knit the first stitch of Row 1. How do i do the rib stitch after that? I mean, how do i do the whole rib stitch in just 7 sts in row 1?

On R 1 you just knit 7 sts, the k1 p1 part of the rib pattern is only done on R 2; knitting R1 instead of p and k gives you the ‘broken’ rib.

So for R 1 in the main pattern, you k1 (edge st) k7 (broken rib), work 15 in small dble cable pattern, k11, 15 dbl cable, k11, work 27 sts of the lg dble cable, etc.