Depending on your kimono, the center back of the collar may have snaps, a string, or possibly nothing. If your kimono has a wide collar (5"/12cm or more) and no snaps or string, you can sew on a string yourself (through the lining, be careful that it doesn't show on the outside). In general, only informal kimono have their collars sewn to worn width. You'll need to fold the collar yourself for all others.

(This helps prevent excess wear on the collar edge when stored, since the collar is only folded when worn.)

For snaps, proceed as you would assume! With a string closure, simply pull on one end until closed. Rest assured that it is enough to keep the collar folded.

Next: Up to the first koshihimo