My program is a bank simulator. I have some questions.

On my program, when I go to a deposit section, when i click $20, how do i make 20 add up to the current balance, what coding do i use.

Also I made a "NEW USER" section where the person fills in information and i want that information to be recorded on a notepad place where the admin or bank can see who registered. Also the new user will make their own pin so when they log in the bank, they enter their pin and they will be able to access their account like a real bank.

(basically, i don't know much of what coding i need to use ex. cmd20 = cmd20 + 20 or w.e)

Thanks~