Welcome to steemit dear friend @oussemakallel, I've met with good friends by searching 'introduceyourself' tag, i love newbies and delight in giving them a hand of friendship. Love from @maxdevalue, am sending some steem to your wallet right away, you'll do great here.
You asked to know more about steemit, well steemit is huge, the more you try to understand it, the more it unfolds, in simple term; steemit is a social network like facebook, but nicer to be compared to other socail networks in the sense that friendship here is globally, not limited to your siblings and old school mates.

your contribution in steemit is also with a reward unlike other social networks, try and invest here through building your 'steem power'. Post things that of your interest but with great value for the community.
Welcome.