As the recommended selection Zipcloud will automatically backup all the files stored inside your 'my documents' folder. By default large files are excluded from the recommended selection, however you can easily raise your file size limit by clicking on 'backup settings' on your application and selecting the 'Backup Selection tab'.
It is important to note that Zipcloud excludes certain file extensions from backup selections. To whitelist file extensions or to exclude further extensions click on the 'File Types' tab located in 'Backup Settings'.