theme support…permissions?

hello,
how do i chnage the permissions on my WP?

the themes i install are always half way missing, and are usually not what I expected from the screenshots Ive seen from the creator.

someone said earlier they had the same problem but they changed the permissions and that was the cause of it. Do you think it sounds like the same problem I have? If so, how do I change it? And if not, what do you think the problem is?

THank you for reading and helping.