public OnPlayerSpawn(playerid)
{
	SetPlayerPos(playerid,0.0,0.0,3.0); //The position where the player will stand when u give him the dialog, (not important)
	ShowPlayerDialog(playerid,1,DIALOG_STYLE_LIST,"Spawns:","1. spawn 1\r\n2. spawn 2\r\n3. spawn  3","select", "cancel"); //Show the player the dialog
	return 1;
}

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[]) //What must happen when the player choose a item from the dialog
{
    switch(dialogid) // Lookup the dialogid
    {
        case 1:
        {
            if(!response)
            {
                SendClientMessage(playerid, 0xFF0000FF, "You cancelled."); //when he types cancel (copied this part from wiki IMO I would do it on a different way...)
                return 1; // We processed it
            }

            switch(listitem) // This is far more efficient than using an if-elseif-else structure
            {
                case 0: // Listitems start with 0, not 1
                {
                    SetPlayerPos(playerid,0.0,0.0,3.0);//if the player clicks teleport 1
                    return 1;
                }
                case 1:
                {
                    SetPlayerPos(playerid,0.0,0.0,3.0);//if the player clicks teleport 2
                    return 1;
                }
                case 2:
                {
                    SetPlayerPos(playerid,0.0,0.0,3.0);//if the player clicks teleport 3
                    return 1;
                }
                // Add the rest of your listitems for dialog 1 here

            }

        }
        // Add the rest of your dialogs here

    }
    return 0; // If you put return 1 here the callback will not continue to be called in other scripts (filterscripts, etc.).
}