first of all, make sure you're logged in. 
Then you do the following: 
go to your user panel, use the jump menu and make sure you select "anime", then click go 
If you have Vista, there is a bug.  You have to just upload to whichever subdomain (in this for instance, anime) then go back and EDIT where the story is.  For a variety of reasons (most prominently an incompatibility issue with old scripting language and Vista) the menu will not work correctly, so you have to take a second step. 
Make sure you select which category you want to upload to, after you select the subdomain.