It can be very confusing to a newbie when observing a match or watching someone play. 3c is usually played with two players. The winner of the lag determines which ball will be his/hers...either white or yellow. Red is always neutral. From that point on, your cue ball will "always" be the color determined by the lag. There are many forms of billiards....3 cushion is just one version. The best way to learn the rules is to just google it. That's what I did when I first started out.
Your cue ball has to strike 3 or more rails and both balls. The key is your cue ball must strike the rails 3 or more times before it makes contact with the second ball. You can chose to shot ball first off red, ball first off of your opponents cue ball, rail first then a ball then 2 or more rails, 2 rails first then off a ball then 1 or more rails into the next ball, or 3 or more rails and then contact both balls. The choice is up to you. It's a beautiful game with so many different ways of playing each layout.
One of the most important things for you to remember is...the balls are bigger and heavier. Watch how the english applied reverses upon hitting the second rail...especially on corner shots. Learn the 3 rail shot into the corner and 5 rail shot into the opposite corner first and foremost. You will see these shots and their variances come up the majority of the time while playing.
Now you're hooked. Good luck and best of shooting.
