I need help with coding...

Well, I am not to write your code for you.

If you want to ask questions about some code you have written that is one thing.

We are not here to do your project for you.

That being said, I would typically implement a data entry function for setting a clock (in fact I have for my nixie clock) using a sequential state machine:

Press button1 to get into set hours tens digit mode.
Then press button 2 to increment the selected digit (ie, hours 10s)
Press button 1 to save the selected digit, and move to the next digit (ie, hours unit).
Then press button 2 to increment the selected digit (ie, hours 1s).

Keep going until get down to seconds 1s digit.

Last press of button 1 sets the seconds 1s digit and enables the clock to start running.

So all you really need is two buttons, no other switches.