If you have shell access to the webserver (and it is running *nix) you can simply chmod a directory using the chmod command. For example:

chmod 777 /home/jamie/Web/fluxbb/forums/cache

or if you wish to recursively chmod all the files within the directory

chmod -R 777 /home/jamie/Web/fluxbb/forums/cache

Warning: remember to check with your hosting company what's necessary before doing anything. chmod files to 777 might appear to work fine on your end, but in fact be a major security breach on many, many hosts.

The exact steps will vary depending on your FTP client, however the general idea is:

1. Open your FTP client and connect to your website.
2. Navigate to your forum root directory.
3. Right click on the folder you wish to chmod and look for an option called “chmod”, “permissions” or “properties”.
4. This should give you a window which will either have check boxes for “read”, “write” and “execute” permissions for “owner”, “group” and “public”, or a text box to enter the value manually.
5. Either tick the appropriate boxes, or enter the appropriate value into the text box, and apply.