"tv" setting to change shutter speed

forget what it stands for but figured out that if I go to that setting I can then use a turn switch to adjust the shutter speed - but faster shutter speed means I need more LIGHT and even at the highest ISO setting (I think my camera only goes up to 1600) it is pretty dark inside with no flash. So I thought - no problem I'll just turn on the flash - problem is that as soon as the flash is on my camera will automatically turn back the shutter speed to 200 which is not fast enough to get a non-blurry picture. Seems I need to read more about my camera and see if I can adjust this problem.