Hello,
I have a problem with Krita and I would like to ask you for advice. Specifically, I can not save or export any file on my computer. The problem is that when I want to click the "save" button, nothing completely happens. I can click a few times and the file does not save anyway.
I am asking for help, because I want to draw in this program.

Can you tell us which OS and OS version you are using and which version of krita you are using? This information would be useful to any developer who tries to help with this problem.

If you've started with a new image, freshly made, then clicking File -> Save (or File -> Save As) from the menu should give you a 'Saving As' dialogue window where you tell krita where to save the file and in which format. If you've already done a Save or Save As operation then File -> Save will not give you this dialogue window, it will just save the image in the filename you previously specified. If you do File -> Export then you should get the Exporting As dialogue window every time.

Is it the case that you never get the Saving As dialogue, even if you do Save As and you never get the Exporting As dialogue when you do an Export?

If so, you can try the following: From the menu bar, do Settings -> Configure Krita and the Configure dialogue window should open. Select 'General' from the left side column and them click on the Miscellaneous tab in the section on the right hand side. At the bottom, just above the 'Maximum Brush Size' value, there is a small checkbox called 'Enable Native File Dialogs'. Whatever is in this box, click it to change the setting then click 'OK' at the bottom of the dialogue window and see if that fixes the problem.

What I suggested is an idea that may or may not work.