Start with:
Control Panel » Forum Permissions
select the gallery forum and use switch to button to bring up that forum's permissions.
At least two permission checks to look at.

Total # of gallery images
Add the number of attachments allowed per user group

Maximum size of gallery images
Read the note this will tell you the max size per your php.ini allowed. You can't exceed that value.

Enter a value for each user group.

The value is in bytes. Not mb or gb. so for say a 1 mb file you would enter 1048576

Oh don't forget to select the update this forums permissions button at the bottom of the screen

Last edited by Ruben; 06/15/2010 5:22 PM. Reason: Added comment

Blue Man Group
There is no such thing as stupid questions. Just stupid answers