She doesn't even have to do that.
She can just set Steam's install directory in Steam itself to wherever she used to have Steam installed. I believe it's in view > settings > downloads > steam library folders. That way Steam just automatically links to what her old install folder was so she doesn't have to copy paste things. Though I'm honestly still scratching my head at why she didn't just install it where she had it before, or how that would have been "too much work" compared to what she has to do now.
I am good with graphics and video software, but I know nothing about code or data or any of the stuff most of you guys seem to take for granted. Here's what happened in detail:
1. Try to open Steam. It starts auto-updating.
2. Update downloads, it says it has to restart Steam. Click OK.
3. Progress bars while it installs. Suddenly, it crashes, says some file is not found (don't remember which) and closes out.
4. Try to restart Steam about ten times, same result each time.
5. Annoyed that update seems to have deleted some critical file. Try to "repair" Steam installation using install file newly downloaded from site.
6. "Repaired" Steam still gives me same error when I try to open it. Getting frustrated, run the install file again and this time select to uninstall the program entirely, figuring I'll just do a fresh install and be done with this.
7. Uninstall runs fully, I get the message the program is successfully uninstalled.
8. Try to reinstall program: get the error message that Steam must be installed to an EMPTY folder.
9. Confused, look in program files and find that all the Steam files are still there despite the supposed uninstall.
10. Extra annoyed now, try to delete entire folder to reinstall. Get error message that Steam is in use.
11. Probably should have used ctrl alt del to find Steam program (apparently still running despite everything) and force close it, but didn't think of that and instead just renamed the install folder to Steam2.
12. New install works fine but all my games are obviously missing. Re-downloaded a couple before learning that I can just copy and paste them from the old folder to the new one.
I still have no idea what the hell went wrong, but I really dislike Steam and I'm not likely to buy through them again. Let me buy the game - great. I download it, and let it run on its own. I don't want to run through your program and I see absolutely no benefit to it other than allowing you to bombard me with ads and control my bought and paid for games. It reminds me too much of iTunes, which I refuse to let on my computer for various reasons.
EDIT: Apparently I can't just copy-paste the game files. I managed to get the app to see the game installs, but the saves are gone and I don't know where they've been stored. Something tells me I will have to start all over in Machinarium, after all the hours I put into it already... Yep, never buying from Steam again. No thank you to constant automatic updates, my games relying on your program working, and the program apparently continuing to run in the background even after you have shut it down.