A lot depends on the nature of the room you are in.

If the ceiling and walls are fairly light in tone and a neutral color then you can bounce the flash off the ceiling. The angle will depend on how far away your subject is as well as how high the ceiling is. Ideally you want to aim the flash at a point in the ceiling that allows the center of the beam to reflect onto the center of your subject. The ceiling will also act to disperse light throughout the room and back onto your subject. If the ceiling is rather high and the distance to your subject is small you may need to point the flash almost straight up. This can create problems with shadows around your subjects eyes and under their nose and chin. Placing a bounce card on the flash to direct a small portion of the light directly onto your subject will help fill out shadows caused by bouncing the flash overhead. If the ceilings are lower and your subject a little further you would need to adjust the angle down a bit.

If the ceilings and walls are darker or tinted then it gets more difficult. You will either have to settle for pointing the flash head directly at your model while mounted on your camera's hot shoe or more preferably move the flash off axis from the lens and point it directly at your subject while triggering it either wirelessly or with an off shoe cable. Any one of a number of modifiers can help to soften the light.

A good place to start if you really want to learn how to use a portable strobe such as your SB 600 is strobist.com