Login with your email address as your User Name and your email password for Password and click Go
*Ignore the contents of this page for now, at the top of the page, put your mouse on UserFunctions and then select "View My Details"
Scroll down and find the blue bar labelled Principal Collections
Identify under Display Name which line corresponds to your calendar (not your address book).
Click the link in the left most column on the identified line. It will be a four or five digit number.
Note the DAV Path, your assistant will need this information to set up their calendar client
Under "To ID Display Name" use the drop down menu to select your assistant's email address
Select the individual permissions to grant to your assistant, or use one of the blue buttons to select a pre-generated subset
All Permissions will do exactly as it says, grant that user full permission to organize your calendar anyway they see fit
Read/Write access allows the user to modify your calendar, such as delete events and create new ones.
Read access will allow the user to view your calendar events, but will not let the user add or delete events
If you know what the other items are, you will know if you need them; else you don't need them.
Click the Grant button.
After you click the Grant Button, The user will be displayed with a link so you can look at the details of that user
The privileges that have been granted to this user will be listed
Use the Edit and Revoke buttons to modify or remove a user's ability to access your calendars respectively
You may add multiple users and grant each of them a different set of permissions
FAQ
Q: Can I use Outlook?
A: Yes, but you will need a third party plugin to edit your calendars. Outlook 2010 can reportedly allow you to read the calendar but not modify it.
Q: When I initially Log in, there is a page with a lot of stuff I don't understand. What is that?
A: Ya, that is documentation, and it isn't really aimed at the layman. If you understand it, great. If not, hopefully this page explains what you want to know.