If the lens you are using is f4ish or greater like an f4.5 - f8 or whatever, then there may not be enough light to use it in this situation and freeze the action. The best way to sharpen up your pics are:
Use a tripod / monopod / beanbag (ok, might not be possible in a sports event, but then again...)
Up the ISO/ASA settings to their maximum i.e. 1600 ISO
Shoot in Shutter Priority mode and ensure that the shutter is 1/length in mm i.e. 1/300th or faster for 300mm and 1/70th or faster for 70mm.
Buy a really expensive long prime lens with a low f-number (ok, probably not a great answer, but you might have lotsa $$$$)
The yellowing/oranging is due to the colour temperature of the lights lighting the event. There are two ways around this - calibrate the WB (white balance) of your camera to compensate and secondly: change the curves/colour balance/levels in photoshop or similar editing program. Actually the sinful button "Auto Levels" sometimes works really well with yellow pictures in PS!
Search on this forum for "sport photography" and "sports" and you should find plenty of previous articles about this. Also, have a look at the basics sticky at the top.
Rob