ozinoz
You need to consider:
Your present Power Supply can it drive a GTX 970? Does it have the correct MOLEX connectors for the new card?
Is a GTX 1060 a better bet?
Monitor Resolution?
Is there enough room on your motherboard (case) to install a new card - they do tend to be a bit taller, longer, and wider these days.
Make sure your PCIe slot on the mother board can support the new card.
If everything is OK its easy to install a video card.
Turn off all power to the PC. Unplug all cables and remove side of case.
Ground yourself against static electricity
Unscrew the back plate holding the old card into the case.
Check if there is a "small lock type device" holding the card in the mobo slot.
Release that and ease the card out, upwards smoothly.
Insert the new card - may be wider than the old one so you may have to remove another metal slot on the case.
Insert the card into the mobo slot pressing EVENLY and making sure any slot on the card matches that on the mobo, and it "locks" into place on the mobo slot.
Tighten the retaining screws the holes will line up if you have the card seated correctly - check the card is seated.
Close the case turn on the power and perform a CLEAN install of the latest NVidia drivers.
Google anything above you do not understand!
Google you tube videos how to replace a video card using the brand and card details eg MSI GTX 1060 or similar and that should help.
Here's a basic video:
https://www.youtube.com/watch?v=5YRlO-55njI Don't rush and don't force anything.
Good Luck
pH