I turned my gas fireplace on and the pilot lit fine and stays on but I can not get the main fire to go on. I have cleaned the thermocouple and other device on other side of pilot and also tried jumping the thermostat at wall and at fire place but no luck.

Is this a self powered (milivolt system) or does it run off 120 volts with a transformer?

I turned my gas fireplace on and the pilot lit fine and stays on but i can not get the main fire to go on. i have cleaned the thermocouple and other device on other side of pilot and also tried jumping the thermostat at wall and at fire place but no luck.
It's a milivolt system self powered

Could be the pilot generator or a safety device wired inline with the generator and valve.

Is there a way of finding this out by myself or is it better to have a Qualified technichen come lookat it?

If you have a volt meter, check for a small voltage across the gas valve terminals. If you have power to it, and it doesn't open it is bad. Otherwise, you need to look for a bad limit switch.

Thanks, how did you know jack dandy is my dogs name or am I drawing to far into this?

Could the thermocouple or a device called a thermopile keep the main flame from lighting?