How to set the timing on a 1990 Pontiac Firebird V6 3.1

Ok so after replacing 2 fuel injectors today to get my car working again, I was finaly able to start it up and give it gas and everythings working great. I notice I was losing some water from a corroded bolt under my intake so I was going to fill up on water and goto autozone to get the part to replace where I was losing water.

As I pull the car over to the waterhose using its idle state and giving it very little gas, I throw it in park and leave it idleing as I fill up on water. I fully fill the radiator, then start on the reserve and as im filling the reserve the engine makes a loud CLANK noise and shuts off.

Now when I try to start it, it doesnt sound right At ALL so me and some buddys narrowed it down to my roter (roder?) Isnt spinning when I try to start the car. Which comes down to my timing chain broke which had to be what that clank noise was.

So now im going to be working on it with my friend (the mechanic) and put on a new timing chain, problem is I know he doesnt have any timing tools and I dont know where to even begin with it so now im here :)

So does anybody know what the timing is sapposed to be set at for my 90 pontiac firebird V6 3.1 L?