Have a read through of the H-Bridge Tutorial I wrote, it explains the ins and outs of a H-Bridge.

Which H-Bridge is it you are using? Which digital port controls the PWM for either side? Is it one common PWM or have you used one for each side?

Use scripts to control them. The enable pins just need a digital high or low, it's all described in my tutorial. So once you figure out what needs to be high and what needs to be low you can write the script to do what you want it to do. If it's for a Movement Panel you will need to use the custom Movement Panel to use all 3.

i am using the one from this site and i dont know what you mean by PWM

OK, do you have the jumpers on the ENa and ENb pins to 5v on the H-Bridge? If not you will need to supply PWM to the ENa and ENb.

Read the tutorial I linked to, it's all in there and it's pretty detailed.

i did all those in fact right motor spins problem is the left one motors are not broken or burned i tested them they just dont work when i connect them to h-bridge

Without a PWM wire you will need the jumpers, check you have both jumpers attached. If you have a PWM make sure it is connected to both of the ENa and ENb pins on the H-Bridge. Or make sure you have 2 PWM connections, one to each ENa and ENb and that they both are set to 100% (or something greater than 10% or so).

Check the output on the H-Bridge. Put your volt meter across the output for the left motor. When the Movement Panel is set to forwards you should get +5V or -5V the same for reverse (but reversed).

Otherwise check your wiring. Unplug the 2 wires from the H-Bridge that drive the left motor. Put your volt meter across each one and ground and set the Movement Panel to forwards, you should get 5V between one of them and ground. Do the same but for reverse, the other one should have 5V. If you don't then your wiring between the H-Bridge and EZ-B needs replacing.

Does the H-Bridge have the LEDs on to say which output is high? Some do, some don't. Mine does but I didn't get it from EZ-Robots. If it does, do these light up as they should or not?

If you have a dual H-Bridge card, can you feed three motors on each of the two ports? and just connect all three motors together?

If you wanted all 3 to work in exactly the same way and if their combined current draw did not exceed the H-Bridge's maximum current limit, yes.

Well you could parrallel the connections. @aameralis - in your situation. A single high quality h bridge like a 2 x 12 sabertooth would be ideal.

@meteal , The community has provided some great answers and I hope you found them useful. Do you mind marking this thread as resolved? Thankyou - Josh