Granting Execute Permission on SQL Azure

I recently migrated a database to SQL Azure. When I try to execute a stored procedure on this database on SQL Azure, I receive the following error:

The EXECUTE permission was denied on the object 'Log_Save', database 'MyDatabase', schema 'dbo'.

My question is, how do I grant EXECUTE permissions to stored procedures (as well as read/write access to tables) on SQL Azure?

thank you!