How can I simulate different realizations of these joint random variables with the given PMF?

If I have two Discrete Random variables X and Y which have the joint PMF:

$P_{xy} = c(x^2 + y^2)$, where $x$ belongs to {1,2,4} and $y$ belongs to {1,3}

I tried to make two discrete random variables but I am stuck on what is the next step.