lets explain this computer stuff

i am new to the computers. i don't know much of anything about them. i hear people talking about lt1 edit and tunercat but i dont know exactly what they do. can you actually tune your cars with these such as fuel pressure, calculations with gear changes and tires size changes, and spark curves? or is this just to store what your computer is doing on a pass down the road? anything that would be beneficial would be great. thanks

Both lt1_edit and Tunercat will allow changes such as gears/tires/etc + MUCH MUCH more. Basically everything you listed except the fuel pressure which isn't computer regulated. You'd need an adjustable fuel pressure regulator for that.

What madwolf said about the tuners. The other thing you will need to be an effective tuner is a data logging program such as Freescan or Datamaster. Those are the programs you run while you drive your car to read information such as o2 sensor readings, spark advance/knock retard, BLMs, ect. You use that information from the data logging to make changes with the tuner program (TC, LT1Edit).

whats the real difference between freescan and datamaster? also, is the extra price in lt1 edit worth it? or just go with tunercat? sorry, as you can tell, i really don't know what i am doing at all.