ABS and front differential

There is a "ticking" coming from my car, sounds just like when a rock is stuck in the tire, someone told me it may be my front differential, something about barrings and oil.I know nothing about cars except when I put gas in them they go. Please help, as I cannot afford to take it somewhere where they can take it all apart and want to fix things that dont need fixin! Also, my ABS light is on.