How to programming simple videogames in java?

Hi guys... i'm new here, i started to learn java some months ago and i really like it, but i'm still a noob. i think that a good way to improve my java knowledge is to programming simple videogames and i'm doing it. I just want that some of you guys give me some advices and tips to programming videogames on java, like how to implement gravity to make simulators and somethings like these... i don't know how to do it yet. I work with the lastest java JDK in Eclipse and sometimes in Netbeans.

thanks a lot for the attention and i hope you can help me... and i'm sorry for my bad english... i'm from Colombia.