Parent posts can't take it easy

So finally got round to editing a series but I'm not sure how to add the parent post when uploading.
Any help ?

Right under the big box for tags is a small box that says 'Parent'

You just type in the number of the parent image in that box.

http://yukkuri.shii.org/post/show/46899/

In this case the number would be 46899.

Thanks I tried to put the whole link in that box lol