The front derailleur (what you call a chain guide-which is something completely different in bikespeak) is a Shimano E-type, that mounts off the Bottom bracket. It does not connect directly to the seat tube (what you call the vertical support bar). A gap is normal between the 2.

The screws you fiddled with are stroke adjustment screws. they limit the inside and outside travel path of the front derailleur. They do not control the height of the derailleur.

Basic derailleur adjustment tutorials are available online from Park Tool, Harris cyclery, and a few other places. And some local bike shops do classes to show you how to do it.

What's the problem again?

As long as the derailleur cage is not rubbing against the tire, it's good. It can be close, so very close (witrhin a couple millimeters), but as long as it's adjusted properly it shouldn't be rubbing.