I am looking into getting one. I am looking for some help as to what motorcycle to start out with. Maybe some tips on ho/where to start.

Start with your physical build....weight and height. And any previous riding experience you may have. I've ridden for years, and was a certified motorcycle safety instructor.

Hmm, well I am 5'7", I weight about 180, medium build. I have no riding experience what-so-ever, never even been on one. I am looking into MSF classes in the spring though.

I'd say take the safety course before buying. I regret not taking it first. Spring of 2003 I bought a new Honda CBR600F4i sportbike having previous year experience on a Kawasaki 400 I figured this bike would be a peace of cake. So I take in down to take the driving part of the exam and manage to dump the bike and flunk the test as well. So my advice would be take the safety course and buy a used bike before getting a new one. Scratches look better on old bikes than they do on new ones.

Will, any opinions as an instructor?

I go out with my brother every so often. I don't have my own bike, but my brother has two so I get to drive whichever one he isn't. One is a 2002 Harley Road King Classic, and a 2003 Harley Davidson Softail 100th Anniversary Edition with quite a bit of modding done to it. The Road king is a very cushy ride, therefore it'* named so. It is very much a cruiser, but the Softail on the other hand, well that'* a whole different story.
For starters go buy an older early 80'* Honda, Kawasaki, or Suzuki, most of which can be had for around $1000-1500 with 10-15,000 miles. My younger brother just picked up a 1983 Kawasaki 650cc (can't remember model, but it'* a cross between a cruiser and a crotch rocket) for $600. Has a dent in the tank and needing an ignition. Otherwise an excellent starter bike -he was extremely lucky as it had $350 worth of new Dunlops with only 50 miles on them.

Start with a V-twin in the 250 to 400 cc range. You can throw a bike that size around. You don't want to feel like you're fighting it. Don't move to the 600 range until you have a year under your belt. Take a course. Not just the test. I thought I was a good rider til I took the mandatory course (US Military requires it). I loved it so much, I took two more advanced courses, and ended up as an instructor.

The point is, don't buy so much bike that you have to fight it. Learn the right way with a bike you can handle, then move up.

I'd say a V-twin in the 400 cc range. Stay away from the I-4'* for now.

I was looking for a sport-bike, would a Katana 500 or 600 be ok. Well, maybe 500?
Also was looking at a Ninja 500 maybe.

I'm not a fan of the Katana, but the Ninja (EX-500) would be a good choice. It'* detuned enough to not want to try to get away from you, and it'* significantly lighter than the ZX6 (which I owned at one time). The disadvantage is that it has a fairly high center of gravity. Your weight and size may overcome that just fine.

And I know how (thanks to a serial thief at Ft Benning) to stop a Ninja in it'* tracks. It'* called a flying briefcase. Well, the rider/thief stopped, the bike went a few feet further (minimal damage).