Assigning variables to a function newton to find a root

I am a super beginner with MATLAB and I am trying to find the root of G(x)=xe^x-N for a general R in the range of f(x)=xe^x. Thus far, I have written:

function x = newton(x0,tolerancem,N)

       %This is where it should return the solution to xe^x=N, for any general N.
end

I understand how to do this to an extend with paper and pencil but I was wondering how I can program this in MATLAB. Also do note that this is self-study and I am trying to learn using computationally for greater comprehension. Any help is appreciated.

[Matt J]

If you're a super beginner to the point where you cannot write any code, this forum isn't the place to start. This is:

http://www.mathworks.com/help/matlab/getting-started-with-matlab.html

[Jan]

I agree with Matt J. We cannot give a rough 20 hours course in form of an answer here.

I do not understand the mathematical part of the question. "Root of G(x)=xe^x-N for a general R" - but "R" does not appear in the formula. "R in the range of f(x)=xe^x", but the function f(x) does not define a range.