You can upload by navigating to the top menu, files, then click on upload.
You can use this to upload whatever stuff you want but hopefully it will be related to the Requiem mod. Having said that, if you do want to upload personal stuff just make sure it doesn't break laws, copyright and stuff like that.
As a thank you to those that donated $10 in the past: your profiles have been upgraded to rank 4 (if you didn't create a profile make one and let me know what your donation email was). This means you can customize your title and a few other bits and pieces. For those who donated $5 or less don't worry I'll figure out something eventually.