When I put pressure on the Tablet with the pen, it doesn't register on the screen.
Hi, This is always a configuration issue and not a bug in Krita. Whether it's possible to fix this configuration issue depends on your brand of tablet, the version of Windows you have, the version of the tablet driver and the version of Krita you're using, See https://docs.krita.org/KritaFAQ#What_if_your_tablet_is_not_recognized_by_Krita.3F for more information, and https://docs.krita.org/List_of_Tablets_Supported for an overview which tablets are known to work, and which tablets are known to come with broken drivers.
Oh, your explanation is so minimal that it might also be another issue, one with the display drivers. If what you paint isn't shown until you touch some other part of Krita, check: https://docs.krita.org/KritaFAQ#Krita_starts_with_a_black_or_blank_canvas_and_nothing_changes_when_you_try_to_draw.2Fshows_a_black_or_blank_screen_on_my_Windows_system_with_an_Intel_GPU