i did not go into any folder to get the wallet.dat file, i simply used the bitcoin-qt interface and used file > backup wallet and then saved that file to the documents folder, then copied to a USB stick.

i understand i can use the terminal and commands but im not familiar with doing that.

however, i suppose that is how i need to do it to make absolutely sure i have the right file/files. If i have two wallets created/set up, will each wallet have its own wallet.dat file? if so, how do i tell them apart? sorry, i know these are likely very basic questions.

getting a second computer to restore the backups sounds like a good idea as well. that will ensure i did everything correctly if i can restore to a new set up.