To chmod a file means to set a certain permission. Few of the most common chmod commands are 775 and 777. To chmod a certain file or a category using FTP client find something like "Change File Attributes" and enter the chmod command script instructions tell you. If you are using Telnet, here are a few commands that you should use in order to chmod a file or a directory:
u = the file's user (or owner)
r = read access
g = the file's group
x = execute access
o = others
w = write access
a = the user, the group, and others.
