timing

If there is any one that could help me it would bee great.
My 95 Metro is having a timing problem. I know the timing is 5degrees BTDC, on the crankshaft,how do i know where it is? Where do need to set the Camshaft in relation to crankshaft? What is a PCM?
The car runs but last year I had to replace all 3 Exhast valves cause they were melted. Cause of to much heat in the combustion chamber. Since then the car ran great until recently. I've tried to change the timing but it will nit work when I set it up according to the Haynes repair Manual(good man.but needs more on engine).
Also my camshaft has 2 numbers on it 60A & 80C. I have been using 80C Cause it lines up with the Dist. and rotor.

any help would be great. Thank you

to line up timing belt correctly pull the front cover off, on the lower gear there is a dot on outside edge of it. look for line or arrow just above it on engine, should be straight up or close to it. set dot so it lines up with that mark. to line up top gear look at dowel pin in end of cam, it should be at pointing straight down and dot oposite it should be lined up with notch in valve cover at top of gear. to set timing once you get it back together look at underhood sticker, there is a wiring plug you have to jump across 2 pins before you can use timing light. sticker will show you what 2 terminals to use, plug is usually located between drives side strut tower and firewall