there are plenty of ways to do it
it is really a matter of coding style and interaction way (buttons, text, actions etc..)the general idea behind it is that you take the stuff step by step - and break it to smaller tasks, which you can later learn by order.
for example:
- how to create buttons
- what are the differences between data storage in singleplayer and multiplayer games
- how to save data according to my game style (inside the player class instance / separate class / struct / component…)
- how to bind buttons to events
mind, there are many other variations of breaking it down. you should find yours, because there is no ultimate way. good luck with your further development.