If we're talking about direction, then "backward/back" or "forward/ahead" are the same. However, there's a difference with "toward/to": to say, for example, that we're going toward Kiev means we're moving in the direction of Kiev (north, east, west, south) but we might finish our journey in a town between Kiev and where we started. To say we're going to Kiev means that it is our destination, and we won't stop traveling until we arrive in Kiev.

Hi, I think it's explain to me, not explain me. Or may be you could say that in slang, i m not sure, better ask a native.

Thank you for your replies)

In some contexts, you could use either 'towards' or 'to' ; however, 'towards' implies a gradual, possibly slower, movement to the end-point, without reaching it. 'He moved towards the door' : he moved in the direction of the door 'He moved to the door' : he went to the door 'I'm working towards achieving fluency in English' [I haven't got there yet, but I hope to do so at some time] 'This research will contribute towards my dissertation' / 'This research will contribute to my dissertation' : both are good.