Change... - See To Change Permissions below!
Invite people - Enter email addresses or names associated with your Google Account address book to select users to share the file with
Can Edit - You can specify if you want users to be able to edit the document, comment on the document, or only view the document by clicking the 'Can edit' link
Notify people via email - You can deselect the option to notify users by email (not recommended)
Add message - You can add a message to include with the file being shared
Send a copy to myself - You can opt to send a copy of the email to yourself as well