Each file in your account can be assigned an individual permission, controlling who can read, write and execute a file or folder. This is often abbreviated to CHMOD, short for change mode.The vast majority of the time file permissions are not a concern as they are automatically set to the appropriate value when uploading. However certain scripts and programs may require specific file permissions and these are often abbreviated into a 3 figure number (644, 755, 777 etc) This article illustrates how to CHMOD a file.
Open your FTP client (we're using Filezilla) and connect. In the right-hand side of the screen navigate to the file or folder you want to change.
Right click on the file and select "File Permissions"
Use the Change File Attributes window to set the required permission. You can use either the checkboxes or the numeric value field.
If chmoding a directory you will see the option to "Recurce into subdirectories". Tick this option if you wish to change the permissions of the files/folders within this directory.
Finally click OK
That's all there is to it. As a rule of thumb most files should be set to 644 and directories 755.