You're picking up across the back neck, so I assume it is a bound off edge. Usually across the back neck you pick up one in each stitch and you say there are only 20, but they want 30. I guess they need a little more fullness than the 20 would give. It is not hard to pick up more stitches. You usually pick up a stitch right in the middle of each stitch, well do that, but you will also need to pick up some between stitches as well. I suggest pick up 1 in the middle of the first 2 stitches, then one in between that last stitch and the next one. Then make them closer for a few stitches, then go back to the first spacing.
Each v is a stitch you have to work with (20) and each l is where you pick up a stitch between stitches. So pick up one in each stitch and, where indicated, between stitches. The result 30 sts.
Starting at the lower right front neck side edge, pick up same number of sts as you did up the outside edge to the shoulder, (this was pick up 4 for every 5 rows
) I'm not sure where they are talking about, but you probably know. It doesn't say to pick it up the same way, 4 sts for every 5 rows, but to pick up the same number that you did where they are talking about. So if you had 10 or 20 or whatever there, pick up that same number between the lower right front edge and the shoulder, then pick up the 30 for the back, then pick up the same number from the shoulder to the lower left front neck.