Hi, and welcome to motorcycles. If you're anything like us, the sport/hobby will consume you. They are absolutely awsome! We've been riding for 2 and a half years now and love every minute of it.
Good on you for taking the course. Safety first!
As far as first bikes go, it depends on what style you want to ride. There are plenty of small cruisers our there. But if you're into sport bikes like we are, I absolutely can't say enough about the Kawasaki Ninja 250. Absolutely awesome bike. We started on a Ninja 250 and have owned it for more than 2 years now. It is very easy to ride, very responsive, nimble and extremely cheep to own and operate.
Also, in my opinion a lot of people make the mistake of moving to a bigger bike too soon. We bought a Ducati S2R 800 after a year and a half of riding but we still ride the 250. When we're riding in the twisties, the Ducati can't loose the Ninja. Of course on the straights it's a different story. The Ninja 250 is a very capable bike and you can learn a lot from it. After two and a half years we are just now thinking of replacing it with a bigger sport bike.
Other good starter bikes include the Suzuki SV650, GS500 and the Kawasaki Ninja 650R but I would personally stay away from the GS500. the Ninja 250 has roughly the same power but is lighter and in some jurisdictions is cheaper to insure. All of these bikes are technically classed as "sport touring" but they are still great fun to ride and very forgiving. Don't rule out the Ducati 695 and 696 or the Honda CBR F4i if you want to start with something more intermediate (the SV650 and Ninja 650R kind of fall into this category too). It also depends on your size, the Ducatis and the Ninja 250 tend to have lower seat heights for those who aren't too confident with their balance but you can learn to shift your weight around to get a toe down if you're short. On the other side, very tall people may find the Ninja 250 a bit small.
A piece of advice, budget for gear. Between the two of us, we've sent as much on gear as we did on our first bike. That's mainly because we bought full racing leathers but even without that it will be a significant amount of money.
You will need:
-Good gloves, preferably leather.
-Riding Jacket
-Boots that provide ankle protection
-Obviously a helmet. make sure it fits. I can't stress this enough. My first helmet felt fine in the store but after 30 minutes on the road I had to pull over to take it off because of the pain. Go to the store and try them on. Take your time and wear each for as long as is practical. If you feel any pressure points you're best to try another helmet. Those "hotspots" can become excruciating after a while.
Good luck and ride safe!