Click the Add Portlet icon.
A window will pop up with a list of all available portlets.
Click the Add button to add a portlet. Available portlets will have a dark colored add button, and portlets which are already in use will have a faded Add button which you can't click.
Click Close.
Note: To remove a portlet, close the Add Portlets window. Click the X on the portlet you want to close. A dialogue box will pop up asking if you are sure you want to remove the portlet. Click OK to continue. Click Cancel to close the dialogue box without removing portlet. Removing a portlet will undo your customized settings.