Hi again, do you have a name?
So, in terms of pins, you will need 5 for buttons (there are many ways to use fewer pins, but we must keep this simple).
You need to decide if you want to multiplex the digits or not. If you do, the code will me more complex. If you don't, the hardware will be more complex, or you will need a larger and more expensive Arduino. Multiplexing means that not all the digits are lit at the same time, but because it happens very quickly, it appears to the human eye that they are are all lit together.
If you decide to multiplex, you will need either 8 pins (1 per segment) + 4 pins (one per digit, with a transistor attached to each) or 16 pins (for the segments of each pair of digits) + 2 pins (one per pair of digits, with transistors). So either 12 or 18 pins for the display.
If you want the display to be really bright, you will need transistors for the segments also (either 8 or 16), but for a prototype this may not be necessary.
So that is either 17 or 23 pins in total for multiplexing, or 37 pins if not multiplexing, or use extra ICs. What do you want to do?
Because you say you are more experienced with programming than electronics, I would recommend one of the 2 multiplexing options.
Your English is good enough, I can understand you fine. Much better than my Spanish, I can only order beers!
You have a few more questions to answer from my earlier post, they will help me (and hopefully others) to help you. I am also a newbie with Arduino, but I am not a newbie with electronics, micro-controllers or programming, so I should be able to help you, with additional advice from others here.
What kind of Arduino will you use?