You don't. The firing order is set by the basic engine design. You have to look up this manual, sometimes it is printed on a label on the engine, sometimes its stamped into the engine block.
Once you know this you would have to turn the engine till the #1 cylinder so it is at TDC (Top Dead Center). At this point the distributor rotor (if your engine actually has a distributor) should be pointing to the terminal for cylinder #1 too.
Now you can use the firing order to connect the wires from the distributor cap to each spark plug.
Once you know this you would have to turn the engine till the #1 cylinder so it is at TDC (Top Dead Center). At this point the distributor rotor (if your engine actually has a distributor) should be pointing to the terminal for cylinder #1 too.
Now you can use the firing order to connect the wires from the distributor cap to each spark plug.
