Beginner knitting help!

[Yogisunflower91]

Hi! I'm wondering if anyone could help me, I'm new to knitting and planning on starting a cardigan project this weekend.
I've never knit a cardigan before, so wish me luck!

My pattern calls for the below:
I'm just confused on the back part, + the instructions when it comes to the sleeves.
"Work in garter stitch for 36cm then cast off one stitch either side to place arm holes"

Pattern is beginner friendly with chunky yarn + 10mm needles.

You cast on 43/45/51 stitches (depending on the size you are knitting), then work in garter stitch (just straight knit stitch) until your work measures 36cm from the cast on edge.

When your work is 36cm long, on the next row you cast off the first stitch (so drop to 42/44/50 stitches) and carry on knitting the rest of the row. On the next row you again cast off the first stitch and work the rest of the row. At that point you ave cast off one stitch at either side of your work (as the second stitch is cast off once you turn the work, so is on the opposite edge to the first cast off stitch). At that point you now have 41/43/49 stitches on your needle.

Hi OP, it's explained a bit better lower down: R(Row)1: cast off 1 stitch, knit to end, R2: cast off 1 stitch, knit to end.
So you cast off the first stitch (do you know how to do that? Knit 2 stitches and then pick up the first stitch and lift over the second one and just drop it. Or just check out the tutorial I've linked). Then just keep knitting as usual till the end of the row. Turn your knitting and do the same thing again. You should have 2 stitches fewer than you did before.