Tridiagonal Matrix Algorithm

I'm taking a Linear Algebra and Matrices class and we have a big programming assignment.... Problem is that I've never taking a programming class....

Here is the Question

Solve using a computer the tridiagonal system of 100 equations in 100

unknowns given by

2x1 − x2 = 101

−xi−1 + 2xi − xi+1 = 0 for 2<= i <= 99

−x99 + 2x100 = 0

Solve this system by first computing a LU decomposition and then performing

forward and backward substitution to obtain the solution.

I would greatly appreciate any and all help!!!!