[Cxnnor]

pawn Code:

CMD:sethealth(playerid, params[])
{
    new user, health;
    if(!sscanf(params, "ui", user, health))
    {
        if(user != INVALID_PLAYER_ID)
        {
            SetPlayerHealth(user, health);
        }
        else return SendClientMessage(playerid, red, "SERVER: Invalid ID.");
    }
    else return SendClientMessage(playerid, white, "USAGE: /sethealth [ID] [AMMOUNT]");
    return 1;
}

NOTE: You need zcmd and sscanf.