command(info, playerid, params[]) //So the start of your command
{
    {
        ShowPlayerDialog( playerid, 100, DIALOG_STYLE_LIST, "Information Menu", "Commands\nRules\n",  "Select", "Cancel" ); // Okay you can edit this and change it but let me walk you through everything!
    }
    return 1;
}

ShowPlayerDialog( playerid //The ID of the player to show the dialog to.

ShowPlayerDialog( playerid, 100 //100 being the number you want to assign to this dialog (max number is 32767)

ShowPlayerDialog( playerid, 100, DIALOG_STYLE_LIST //The type of dialog you want it to be.

ShowPlayerDialog( playerid, 100, DIALOG_STYLE_LIST, "Information Menu" //The title on the dialog

ShowPlayerDialog( playerid, 100, DIALOG_STYLE_LIST, "Information Menu", "Commands\nRules\n" //What the player can select

ShowPlayerDialog( playerid, 100, DIALOG_STYLE_LIST, "Information Menu", "Commands\nRules\n",  "Select", "Cancel" );// Select or cancel will be displayed at the bottom of the text box, change this to what suits you.

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[])
{

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[])
{
    switch(dialogid)
    {
        case 100: // Whatever number you assigned to your dialog!
        {
            if(!response)
            {
                SendClientMessage(playerid, WHITE, "Hmm ok you cancelled!");//If they select cancel
                return 1;
            }

            switch(listitem)
            {
                case 0: // The amount of cases will be determined by what the player can select! Note always start with case 0!
                {
                    SendClientMessage(playerid, WHITE, "commands go here!" );
                }
                case 1:
                {
                    SendClientMessage(playerid, WHITE, "rules go here!" );
                }
            }// You can always add more cases! If you don't want to use return 1;
        }