hi,
it depends on wheter you want to use the photopost user signup system or integrate with one of the suported forum software packages.Those permissions denied errors well if you are sure you did set them then there is something else you can do.Some hosts do not allow chmod 777 on there servers (security) in that case you need to contact them and ask what values you should use.Also if PHP safe's mode is enabled photopost will not work on your server you can see this by running
Code:
Content visible to verified customers only.
safe mode => off
also make sure you set your permissions like
mentioned here