When doing a timing belt there are 2 ways to start puting it back together.
1. If there is markings on the cam and oil gears and behind them. You would need to match them up. Also there should be a timing mark on the crank like a nick or a cut and somewhere there should be a gauge with a notch at the 0. Sometimes the guage is on the timing cover and sometimes there is a notch on the block with a timing guage on the crank gear. You want the notch to line up with the 0 on the guage. There shouldn't be a need to retime your motor. Once everything is lined up put the belt on and roll the motor 2 full rotations then tighten the tentioner. Turn the engine 1 full rotation and make sure they line back up with the tentioner tight.
2. If there isn't a timing mark on your crank shaft you need to find top dead center. there are a few ways to find this. One is by pulling the crank shaft gear and putting the tooth notch up then replacing the rank gear. Another is to pull the plug on cylendar 1 and stick a screw driver in the hole. Turn the engine untill the piston hits the tip of the screw driver then just before it starts to go back down stop. That should be TDC (top dead center).
Once you have the Crank at top dead center then you would do everything from the first part minus moving the crank.
This is a general explanation for replacing a timing belt so there may be more may not be more that needs to be done.
Also the markers on the gears are usually triangles or diamonds. Sometimes these gears are used on multiple engines and will have both a triangle and a diamond. Make sure you know witch one to use. Sometimes you can find out this info online or maybe someone can answer that question.
Oh and GOOD LUCK!