Creating Large projects

I have been working with Java since September. I've created small applications such as pong, a gui 4-function calculator, etc. However when I try to write a program which is large, I seem to get lost in my code or don't know where to start.
Do you guys have any suggestions on how to overcome this? Should I study code from larger projects, continue to work on smaller projects, or maybe try to simply add to an open source project?

Thank you for your time and effort,

Joseph Pond

Suggestion: break the big problem down into small problems / classes and then solve these small problems in isolation. One step at a time, and you can solve this.