Hi Chipp!
Guess it could be more intuitive - there is no method on the start page:

Like it sez:
"Categories: Click on a category to suggest a link or sub-category"
Once you've selected a category, there are "Suggest Link" and "Suggest Category" buttons on the horizontal button bar near the top of the form.

You can only enter "suggestions", then i have to approve them before they show - that's to protect from the many spammers who try to add viagra links and such. On my approval, you get an email - if you provide an email address.

Thanks for helping out!