How to do the timing in a 325i engine?

i changed my head gasket and i think the timing is off

the check engine light said timing to advance
How to do the timing in a 325i engine?
Does the car start did you align the marks so that #1 cylinder is at TDC if you did that then what you have to do is set ignition timming you do this by hooking a timming light and turning the distributer and setting it to what ever the specification is
How to do the timing in a 325i engine?
You mean to tell me you changed a headgasket? I find that hard to believe. Did you shave the heads? This is a very difficult job on a BMW. Timing is just as bad.