The default permission is edit - click Edit to change the permission
Permissions allow the following...
Contributor - People can make changes, accept or reject suggestions, and share the file with others.
Commenter - People can make comments and suggestions, but can’t change or share the file with others.
Viewer - People can view, but can’t comment or change/share the file with others.
A specific message can be entered that will be included with the sharing email notification - if you do not want to send a notification, click Skip sending notification
Click Send (if sending a notification) or Add (if not sending a notification)