Click on the OK button. Click on the user in the Users list to make sure the correct one is selected. Now, you can now specify the permissions you want to give to the user. You can then set the permissions for each item separately.
None Gives no permissions to the selected user.
Read Allows the selected user to read items, except for items marked as private. Create Allows the selected user to read existing items and create new items, except for items marked as private. Modify Allows the selected user to read and modify existing items, except for items marked as private. Delegate Allows the selected user to send and receive messages on your behalf. A delegate can modify all parts of your schedule, except for items marked as private.