Velocity and acceleration follow the same conceptual framework as in one dimension. For instance, assume that said two dimensions are the x and y axes. Then
vy(t)=dtd(y(t))
vx(t)=dtd(x(t))
Similarly, acceleration works in much the same way:
ay(t)=dtd(vy(t))=dtd(dtd(y(t)))
ax(t)=dtd(vx(t))=dtd(dtd(x(t)))
Furthermore, as velocity and acceleration are vectors, the magnitudes of the velocity and acceleration can be found by means of the Pythagorean Theorem:
∣v(t)∣=vx(t)2+vy(t)2
∣a(t)∣=ax(t)2+ay(t)2
In summary, if you know the position vectors in both dimensions, you can find the velocity and acceleration in both dimensions, as well as the overall magnitude of each.