Updating from version 2 to 5

I’m trying to update my publication’s Ghost 2.7xx to the latest version, but it seems more complicated than just waiting for version 5.x to download. I would need to almost reinstall ghost and copy all my publication’s previous work onto the new ghost.

I’m not sure how to even “reinstall” ghost. Would I need to make a new account?

Tldr, can I get a step by step explanation on how to go from Ghost 2.7xx to 5.x and how I might transfer all the information already in my publication’s website?