l was wondering if there is anyway to put a navigation system in a 2001 lexus rx300..like maybe put it through the little screen thats already in the dash? can you do that?

Yes you can. If your dash is a 'double din' dash, then you can easily replace the factory stereo system with an aftermarket stereo/navigation unit. There are PLENTY of those on the market, and l suggest one of the Eclipse (not the car) units. If you have a 'single din' dash, then it will require some extra work, and cutting of the dash. Still doable though. Best of luck!