Once you've gotten to the top of the display, pick up stitches along the edges of the display and join them on circular needles with the ones from the top of the display and the top of the keyboard. Knit in the round for a few rows. Then start decreasing. I had 242 stitches, so I decreased every 22 stitches, making for 11 fewer stitches in the next row. Use whatever numbers work out for your total (even divisibility). Only decrease every other row, knitting a plain row in between. In the next row, decrease with one fewer stitch in between decreases, in my case 21. Knit a plain row, then repeat the last process, counting to 20, then 19, etc. Until you have the hood the size you want, it took me about 30 rows. Knit in the round until the hood is long enough to comfortably reach the face when sitting in a natural position.