Pick some sources to start with, (as you mentioned acis installed without any issue, thats good.) and start exploring every thing until you can create something by your own. A weapon , a code or something bigger. As a begginer, don't searching for the best sources arround (that cover your needs) because you will give up. There are hundreds of free sources out there, but most of them are outdated with probably different java version than you and with different structure about their static data.