You can post them here in the forums under the "Fanon" category. The rules for that category are in the guidelines and they state as such:
FANON THREADS
1. G and PG-rated content only.
2. Only post your own original work.
3. Only 1 fanon material is permitted per user per day.
If there are a lot of pictures (maybe >5), I would recommend instead of posting them individually in a new post each time, maybe post them all in one thread or instead provide an external link to a different site where you have them up (like DeviantArt).