Change startercharacter with script?

I tried to create a roblox GUI where there are 2 classes, and when you pick one of the two, your model changes to the one its supposed to be, I tried

game.starterplayer.Character2.Name = "StarterCharacter"

If your trying to change something current on the player you need to use local player or PlayerGui. Starter Character will only affect new players joining the game, and you would need to change it from a server script.

how would I change their model though?

What do you mean?
Starter Character–Gear for the player on death or joining
Starter Gui–Gui given to player on joining
PlayerGui–Current Player gui
workspace.Player-- Player Model itslef

How would I change them into a morph from a gui button?

You would take the input from a Gui button, Set off a remote event in replicated storage. a server script would pick that up and than you would change the characters avatar from there(idk how to change the avatar)

ok thank you for telling me…