Put a whole current in a field and every moving charge in it gets the same sideways shove — added up, that is the motor effect: $F = BIL\sin\theta$, read aloud F equals B I L sine theta. $F$ is the force on the wire in newtons; $B$ is the field in teslas; $I$ is the current in amperes; $L$ is the length of wire actually inside the field, in metres — not the length of the whole wire, and examiners know you know that; and $\theta$ is the angle between the wire and the field lines, with the same sine as before.

Two parallel wires need no external magnet at all: each one sits in the field the other makes, so they push on each other. $F = \dfrac{\mu_0 I_1 I_2 \ell}{2\pi d}$. Here $I_1$ and $I_2$ are the two currents in amperes (the subscripts only number the wires, no order implied), $\ell$ is the length of the parallel run in metres, $d$ is the separation between them in metres, and $\mu_0$ is the permeability of free space, $4\pi \times 10^{-7}\ \mathrm{T \cdot m/A}$. Learn the tidy consequence and you can do these in your head: $\dfrac{\mu_0}{2\pi} = 2 \times 10^{-7}$ exactly.

Direction, in one line: currents running the SAME way attract, opposite ways repel — the opposite of what charges do, and worth saying out loud twice. And read the question before you answer it: force PER METRE and force on the WHOLE run differ by a factor of $\ell$, and that is the single most reliable mark lost on this page.