In groups, you can add a file to a page.
Pages is designed to open to the front page for a group, if there is a front page selected. Click the View All Pages button to select a page from the Pages Index.
Open Files Folder
Click the files folder. If there is a subfolder, the course files folder will expand.
Select Link Location
In the Rich Content Editor, place your cursor where you wish to insert your file.
Insert File Link
In the Content Selector, click the name of the file  you want to insert into the Rich Content Editor. The name of the file will appear in the Rich Content Editor  and flash yellow. Then the name will turn blue, indicating it is a link.