phpBB has a variety of extensions available. You can check them out here. For this guide, I'm going to use the Linked Accounts extension as an example.   Download the linked accounts extension. Extract the zipped folder you downloaded. The folder extracted will be called flerex and within that will be another folder called linkedaccounts. Now use your FTP manager to access your site. Not sure what that means? Read this guide. On the local site side of your FTP (