Here is a bullet point list haha |D And luckily it's a free feature!

• First create a submissions folder to put your featured stuff in.
• While you're still on the general Settings > Submission Folders page, scroll down to "Edit Folder Options" and select the folder you just created.
• Check the box for "This is a featured submissions folder" and save.

If the folder has multiple submissions in it, your profile will display one random submission from just that folder.

It kinda sucks that you can't put submissions in multiple folders to keep everything organized, but maybe someday... I hope this wasn't confusing ;w;