how do I replace a broken U-Joint on the front (4x4) drive shaft and put the now removed drive shaft back in -without going to a mechanic?

I have a 1990 full-size Eddie Bauer Bronco. This is my first 4x4. I put it in 4low and 4high one night and drove at about 3-5mph up my driveway and back,about 60 yds. had a heck of a time getting it out of low. Next day broke driveshaft (4x4) and cracked transfer case adapter. Found another cast iron adapter had mech put it in. Bought universal joint and rear trannie seal after removing driveshaft myself.Mechanic told me my driveshaft(u-joint) broke because I drove my truck in 4x4 on the pavement. Please advise me what to do. I am not a mechanic but am learning everyday what I can do myself -one of the main reasons I love older model vehicles.