Low compression, all Cylinders...how do I replace timing chain?

What is your question?

I have a '07 G6 GTP, I have spark, and I have gas...my thought is it should go boom...tried ether and still nothing. It will crank but thats it. I used a compression tester and only have 30 lbs of pressure on each cylinder which i believe is supposed to be like 125 lbs. I am most certain it isn't a bent valve so my only other thought is timing. Can anyone tell me if it is computer controlled or is there a belt or chain and how to fix this? Thanks