when you connect to a sever (if you wants sources you should be using emule:
http://www.emule-project.net), try and connect to one with a low ping but a high usercount. Razorback2 is the best for me, but depending on your geological positioning it maybe another server for you.
When you connect, you should idle for a while. Sources will appear.
In preferences under connections, you should set an appropriate number of connections, you can get help here:
http://www.dead-donkey.com/modules.php? ... Newbie+FAQ
In the little box on the right where it says "My Info", you should have a six plus sting of numbers and "high-id". If you have "low-id", you are firewalled/blocked and will not be able to get sources.