I'm trying to get a new number into my room, but am not sure how to change the wiring on the jack. My service provider is charging $120 to just change a couple wirings on the jack. There are 3 main wires coming out of the jack, and the 4 different color wires attached to it. How do I change the wiring to be able to get a different phone # assigned to my room?

If you are trying to bypass illegally, sorry, you won't get that info here.

The phone company has to install a terminal block at some point in the house for the new number. That terminal block will either have a regular RJ11 jack on it or a terminal with four wires. All you need is the red and green wires to connect to the jack in your room.

Is this new number going to be a 2nd line into the house? If so, then as ScottGem says there will be terminal block somewhere that allows you to connect in whichever extensions you want to have for the first and second lines - no need to do anything at the jack in your room. However, if you'd like to use a 2-line phone in your room, then some wiring changes will be needed - post back if you need further info.

If Phone Company added second line , they will be on 2 terminals. Usually older phone wire is red and green for line 1, and Yellow and black for line 2.
Just connect yellow and black to unused terminals(should have about 48 volts).
If second line is going to fax, then take the yellow wire, and connect to red(on jack), and the black wire needs to connect to green.
Red and Green are center pair and any single line device will plug in an access that line,
In this case, it would access line 2.
A 2 Line phone plugged into jack, using red, green, yellow, and black(line 1+2), and a 4 wire Line Cord, will work.