how do i make gamemodes like FFA,TDM etc and How do i make Map voting and Gamemode voting GUI? ?

How do i make Gamemode and map voting GUI.Ive been searching YT and never found any tutorials on how to make gamemode voting gui pls can someone answer my question.

I want to make a GUI that asks the player to vote both map and what type of gamemode eg FFA,Control the point,TDM etc.When the player chose a map i want the map to spawn near the lobby.With team asigner if chosen any team match or if ffa was chosen the teams wouldnt be assigned but the problem is i cant make any team gamemodes because the game is automatically only FFA i cant make any sort of team gamemodes

Pls answer my question briefly im not an experience coder.