There are two main ways of changing permissions for your files and/or folders. Both of which include the usage of the following tools:
1. File Manager - Navigate to the file or folder which permissions you wish to change, right-click on it and choose 'Permissions' option. You will be able to enter the desired value in the following window.
2. FTP client (ex. FileZilla) - Similarly to the previous option, you will need to find the file/folder, right-click on it and then look for either 'CHMOD' or 'Permissions' option.