CMD:myid(playerid, params[])
{
    new string[90]; //this is enough for the line "Your id is %d" - we will gonna format the word "Your id is %d"
    format(string, sizeof(string), "Your id is %d", playerid); //will gonna format the word "Your id is %d" with string/playerid and gonna use on SendClientMessage - %d - Inserts an integer (whole) number
    SendClientMessage(playerid, -1, string); //this will be sent to the player who type /myid with the format string
    return 1;
}

CMD:jetpack(playerid, params[])
{
    new string[90],pname[MAX_PLAYER_NAME]; //string 90 is enough for line "%s has spawned jetpack"/we will define pname with GetPlayerName
    GetPlayerName(playerid, pname, sizeof(pname)); //pname is define here 
    format(string, sizeof(string), "%s has spawned jetpack", pname); //will gonna format the word "%s has spawn jetpack" with string/pname and gonna use on SendClientMessageToAll - %s - Inserts a string.
    SendClientMessageToAll(-1, string); //this will be sent to the everyone with format string.
    SetPlayerSpecialAction(playerid, 2); //Spawns a jetpack to the player
    return 1;
}

CMD:me(playerid, params[])
{
    new string[128],pname[MAX_PLAYER_NAME]; //this is enough for the line "%s %s"/we will gonna define pname with GetPlayerName
    GetPlayerName(playerid, pname, MAX_PLAYER_NAME); //pname is defined here with GetPlayerName
    if(isnull(params)) return SendClientMessage(playerid, COLOR_RED, "SYNTAX: /me <text>"); //if player didn't type something this message will be showed example if you type: /me only the word will be showed
    format(string, sizeof(string), "[ME]: %s %s", pname, params); //will gonna format the word "[ME]: %s %s" with string/pname/params and gonna use on SendClientMessageToAll - %s - inserts a string.
    SendClientMessageToAll(-1, string); //this will be sent to the everyone with format string.
    return 1;
}