So I'm the creator of: https://e621.net/post/show/1871395/absurd_res-bow-celrise_-floraverse-city-clothing-c, and I was wondering how to add a new character that hasn't been cataglorized on e621 before without running to the forums for help.

Also if some could add the three characters to the correct space that would be great.

From the howto:tag_categories page:

All members can use the tag index to change a tag's category. On the page, enter your tag in the Name field to search for it. (If it existed before but doesn't have any active posts, toggle the "Show empty tags" checkbox.) If the tag you're looking for appears, appears click on "edit" under the Type column on the row for the tag to change it. On the edit page, click on the Type drop-down list and select the category you want. Click the Save button, and you should be brought back to the tag index with the message "Tag '<tag_name>' updated" on top if the change was successful.

I've already changed the characters' categories for you.