Attaching a file to a forum

[ForsakenSounds555]

Hey guys, I'd like to start my arrangement topic to start getting feedback before turning in a submission, but I literally got stuck on the first step: attaching the files. Dragging and dropping the files onto Chrome just downloads them (thanks Chrome), and it looks like the inserts above are just for urls. Any help is appreciated.

[KoryGlover]

I also searched but could not find where to attach the document.