You have the rights to post pictures in the Photo section. You might be getting some error . Please post the pictures again and I think you will not get any error.
Some suggestions,if it is still happening :
1. Do not write Title of the photo in more words .You can post more details in the description section.
2. Login in your account before posting photos because some time when you are uploading any pictures then due to network problem,you might get logout automatically.So,in that case,you will get a message like you do not have permission to add.
Note: Do not post irrelevant photos in this section. Also,avoid extra dots (like ...) in title and description too.
Feel Free to Ask any Query in Forum Section.