Install backend part of N1ED
N1ED is a client-side script. This means it can work with any components installed on the server. But if you want to use any file functions, you must install the backend of Flmngr file manager. Even if you have not purchased the Flmngr add-on, its server part is still available to you in the limited functionality mode: you can upload files and embed image galleries in any case.
Use one of these manuals depending on your server environment (language/platform):