Well you need to make it
On the Buddy List window, click on the "Edit" menu item. Select the "Settings" menu drop-down item.
In the "Settings" preferences, select the "Expressions" tab.
In the Expressions preferences, click on the "Browse" link.
Select your icon with the "Select A Buddy Icon" tool. Keep in mind that your buddy icon needs to be 48 x 48 pixels and no more than 7K size.
Click on the "Save" button.
If your picture is not that small, you have to make it 48x48 pixels.
Go to this icon maker and browse-->upload the image from your desktop. It will make it the right size.