There is a tutorial on Google which explains How do I manually track clicks on outbound links?
However that tutorial doesn’t help a lot for non-geeks.
This is my effort to simply the outbound link tracking.
Assuming that you are using Asynchronous Google Analytics Tracking Code follow these steps
Add following code just before closing head </head>
For each external/outbound link which you want to track add the tracking information
<a onclick="recordOutboundLink(this, 'External Website', 'externalwebsite.com');return false;" href="http://www.externalwebsite.com">
You can find this outbound link tracking report under Google Analytics Content->Even Tracking
You can see more details on this report from the menus in left.