What exactly are you given? If you are just given the center of such a circle and a point on the circle, that doesn't uniquely define the circle.
Assuming you are given the center and the boundary of the circle, here's an idea, but there might be an easier way. (I don't know how much you already know First change coordinate systems so that the circle is in the $x-y$ plane; if your current system is $(x,y,z)$ coordinates, then change to $(x',y',z')$ coordinates, defined by
$$
\begin{pmatrix} x' \\ y' \\ z' \end{pmatrix}
= R
\begin{pmatrix} x \\ y \\ z \end{pmatrix},
$$
where $R$ is an appropriate rotation matrix. One way to calculate $R$ would be to view it as a composition of "simple" rotations, namely, rotations about each of the axes, and think about what the rotation would need to do to get the normal vector to the circle coinciding with the $z$ axis.
For example, if the normal vector was $(-1, 0, 1)$, $R$ would be the rotation matrix that rotates vectors in space $\pi/4$ radians clockwise, so that the new normal vector would be $(0,0,\sqrt{2})$, so that the circle lies in the $x-y$ plane.
Then parameterize the interior like normal ($(x')^2 + (y')^2 \leq r$), then transform back to $(x,y,z)$ coordinates.
One more thing: if the center isn't at the origin, you'll have to shift so that it is at the origin, since linear algebra likes things to be at the origin.