You can share a document using the BuddyDrive shared drive either to a group or on your profile.  Or you can post the file on your wall.

You can post the document via Post to Group or through View Documents then :-

1. Navigate to the folder where you want to post the document or click to create a new folder.
2. Click to add a new file.
3. Drag or select file to upload.

Once your file is uploaded it is available to members of the group.

Additionally you can add a description to the file and add change its visibility and even add a password to access the file.  You can also delete the file.