you will have several mountains. ( i know i am super with technical terms)
half double in the back of the next stitch, just the back loop so you get that raised zig zag
and a double in the back loop of the center between the mountains. and so on
i did 11 sets of these two layers and in the last fill layer just crocheted to the first row to close the tube up. remember to leave a space for the thumbs though. . . .yeah, i forgot on the second one.
this is a picture of the closing line from the inside and outside. the inside has this seam and the outside looks continuous. i was pretty impressed since i was making stuff up as i went along.