1993 Jeep YJ SMOKE and more SMOKE

Ok I have a 93 jeep wrangler sahara edition and here's the problem: The other day I could tell the jeep was losing power and when I would stop it was almost like it wanted to die, so when I would take of a stream of smoke would come out of the exhaust and then go away, "it did not at this time smell like oil." Now to the big problem: I went to the auto parts store to get spark plugs and a guy came up to me and ask me to raise my hood so he could look at it. Opened the hood and found the oil stick was slight out so it was blowing oil all over. Well I bought some oil to replace what had been lost and here's what happened: He put the oil in it started up and was fine so I shut it off. Then as I was leaving the lot it started smoking like it was making clouds and now there is something black "don't know if it is oil or what"pouring out from the bottom of the manifold where the exhaust pipe starts and the same thing is coming out of my tail pipe. I checked the oil once it had cooled down and He put way to much oil in it it is about 3 inches passed the full line, "I am going to drain to get to the normal level though." Any help to get this fixed from black stuff from pouring out and smoke stopping would be sooooo appreciated!