matrix for linear transformation

Last question ever, I promise.

If T is a linear operator on the space V and the eigenvector of T is a non-zero vector v in V such that Tv=av for some scalar a. Suppose that V is finite-dimensional and that B is an ordered basis of V such that the first vector v is an eigenvector and a is the corresponding eigenvalue. Show that the first column of [T]B has a as its first entry and the rest of those entries are zero.

I have absolutely no idea what to do here.

Any help would be appreciated.