Outlook 2010

Click on Calendar > Right Click on your Calendar > select Share > Share Calendar

You will then get the below box, with the ability to select who you want to share your calendar with, and the details you want them to be able to see. (Availability Only, Limited Details, Full Details)

To change the calendar permissions, right click on your Calendar, select Share > and select Calendar Permissions, and you will get the below Calendar Properties window.

From this window, you can select the person you want to adjust the permissions for (step 1).

And select their Permission Level (step 2).

Once done adjusting this, please click Apply and then OK, and they should then be able to see your calendar with the adjusted permissions you gave them.

Outlook 2007

Click on Calendar > Right Click on your Calendar > select Share > select Share Calendar

You will then get the below box, with the ability to select who you want to share your calendar with, and the details you want them to be able to see. (Availability Only, Limited Details, Full Details)

To change the calendar permissions, right click on your Calendar, select Change Sharing Permissions, and you will get the below Calendar Properties window.

From this window, you can select the person you want to adjust the permissions for (step 1).

And select their Permission Level (step 2).

Once done adjusting this, please click Apply and then OK, and they should then be able to see your calendar with the adjusted permissions you gave them.