Ninja is a great pool to mine on. Short version, to start mining with a pool you just need to set you reward assignment to that pool, then point your miner at the pool - no signup required.
Longer version, you need to configure the jminer.properties file - something like this:
Plot paths is the drive/path to your plot files, numericAccountID is your numeric burst address, platformID and device ID will vary depending on your PC, but will most likely be 0,0 0,1 or 1,0
Better version, come over to http://chat.burst-team.us:3000/channel/general and I can work with you to get it all running.