You're right. I don't have a clue as to the role individual components play. I do know, when my heat is working properly:
1. evacuation blower starts for 45 seconds
2. after 45 seconds, ignitors click once or twice and burners light
3. air handler blower comes on to distribute heated air

Currently, evacuation blower and ignitors start at time, burner doesn't light. I do not mind replaceing the most likely components, because local technicians around here will do so as there means of troubleshooting. I'm just trying to cut out paying someone else labor to sub in components until it works.