Momentum is usually defined as $$ M = r \times F $$ where $M$, $r$ and $F$ are vectors and $\times$ is the vector product.
$M$ is the resulting momentum vector, it is normal to the plane of a resulting movement, where a force $F$ acts on a point at a position given by the radial vector $r$.
Right hand rule: Your thumb points in the direction of the vector $M$, your fingers show the direction of the resulting movement.
In the animation above you see the radial vector $r$ (red arrow), the attacking force $F$ (blue arrow), the resulting momentum $M$ (light blue arrow, pointing upwards=counter clockwise movement or pointing downwards=clockwise).
Further linear momentum $p$ (green arrow) and the angular momentum $L$ (light green arrow).