The cam sprocket and the aux sprocket are identical. They both should have marks on them.
The easiest way to "time" the belt (if it already runs fine) is to remove the covers, line up the crank sprocket with the mark on the seal holder, double check if the cam sprocket lines up where it's supposed to, then change the belt without moving anything. I find it easier to make a mark with a yellow or white marker on the sprockets and covers but that's just me. Make sure to take the slack out of the driver's side of the belt when installing it.
Now then, if you don't have a timing light to check the IGNITION timing, you can borrow one at most any parts store. They charge you for it, but refund you in full when you bring it back. That's how their "loan-a-tool" stuff works. You will certainly want a timing light because there's no other way to check the ignition timing on these engines. You want it at 10° BTDC (NOT ATDC!), at idle, with the spout pulled out of the harness connector. Personally I like to verify that the timing pointer is truly TDC by removing the #1 spark plug and using a screwdriver pushed against the top of the piston while turning the engine by hand. When you get to TDC, the screwdriver will stop moving and begin to move again as the piston starts going back down the cylinder. Takes a few tries to get it right. Once at true TDC, look at where the mark on the pulley is in relation to the "pointer" on the cover. It should be zero.
The easiest way to "time" the belt (if it already runs fine) is to remove the covers, line up the crank sprocket with the mark on the seal holder, double check if the cam sprocket lines up where it's supposed to, then change the belt without moving anything. I find it easier to make a mark with a yellow or white marker on the sprockets and covers but that's just me. Make sure to take the slack out of the driver's side of the belt when installing it.
Now then, if you don't have a timing light to check the IGNITION timing, you can borrow one at most any parts store. They charge you for it, but refund you in full when you bring it back. That's how their "loan-a-tool" stuff works. You will certainly want a timing light because there's no other way to check the ignition timing on these engines. You want it at 10° BTDC (NOT ATDC!), at idle, with the spout pulled out of the harness connector. Personally I like to verify that the timing pointer is truly TDC by removing the #1 spark plug and using a screwdriver pushed against the top of the piston while turning the engine by hand. When you get to TDC, the screwdriver will stop moving and begin to move again as the piston starts going back down the cylinder. Takes a few tries to get it right. Once at true TDC, look at where the mark on the pulley is in relation to the "pointer" on the cover. It should be zero.