The problem is "Find an explicit trivialization of the tangent bundle of $\mathbb{S}^{3}$", but I am confused because aren't all trivialization's of a tangent bundle just $\Phi(v^{i}\frac{\partial}{\partial u^{i}}|_{p})=(p,v^{1},...,v^{n})$? How can you get any more explicit?
EDIT: How hard is it to find a global trivialization of $\mathbb{S}^{3}$?