Could you raise the front end of a 2wd by adjusting the torsion bars, or is it that only 4x4 have the option to do that? Please let me know, and if so can somebody kindly share their knowledge with a "how to" guide.

2wd trucks do not have torsion bars ....

Only 4x4's have torsion bars, 2wd trucks have coil springs.

So, while you obviously can't crank the t-bars, you can, however, put on a pair of coil spring spacers, like those linked below.

http://www.suspensionconnection.com/cgi-bin/suscon/KG09100G4.html