Well, on the penultimate row, you'll be doing 22 increases. (22 stitches will become 44 stitches.) On the last row, you'll do 44 increases. (44 stitches will become 88 stitches.) Then you'll bind-off 88 stitches, which is the exact same amount that you cast-on in the beginning.
As for types of increases, that's up to you and the look you want to create. The simplest ones are probably "knit into the front and back loops" and "purl into the front and back loops" which are done pretty much the way they sound. Check out this page for a full listing of increases and videos of Amy doing them.
You're working this scarf in stockinette right? (Since you're K2tog'ing the first row and P2tog'ing the second row?) Then you'd increase in the pattern you've established, either KFB'ing (knit in the front and back loops) or PFB'ing (purl in the front and back loops) the penultimate row depending on whether you've purled or knitted the row before that, and doing the opposite increase on the last row before binding-off.
Clear as mud?