$\displaystyle F=yi+xj$, c is the circle $\displaystyle (x-5)^{2} +(y+1)^{2}=9$

I guess the problem I'm having is parameterizing the function of the circle. Any help would be appreciated. Thanks

EDIT: Maybe parameterizing isn't the correct term. I'm looking to make the equation of the circle look something like $\displaystyle r(t)=cos(t)i +sin(t)j$ or something. From this point, I'm pretty sure I can work the rest of the problem.