I need to find a basis for the orthogonal complement of the subspace $\displaystyle \begin{array}{cc}t\\-t\\3t\end{array}$ that is orthogonal to the basis vector obtained by letting t = 1.

Ok so i think i need to find a vector that is orthogonal to this one, which means that i just dot product with another vector. I just don't know what vector to use, or exactly what to do with the t bit.... Any help will be appreciated thank you in advance.