The hard part's over. To finish your steek, all you have to do is fold back that stitches that formed the steek to the wrong side of the work and sew them down using yarn and a yarn needle.
Make sure as you go that you're sewing evenly along the side, not letting the steek stitches show on the right side of the work and not pulling the first column of pattern stitches onto the back of the work.
If you happened to nick any of the stitches while you were cutting the steek, you can cover that mistake with sewing now. If you didn't weave in your ends, you can also hide the ends in these seams so you don't have to worry about them. This does add bulk, though, so you might not want to do it, say, on a cardigan front.
Finish the other side of the steek in the same manner. Marvel at your knitting mojo and don't fear steeks again!
