Discussing the wallet backup is fine here.
If you've backed up the wallet using the PPCoin-Qt interface, and the wallet.dat file has been written to your USB thumb drive, you're doing it right.
Now, should you at any point in the future need to use that saved file to rebuild your wallet, it's a pretty easy process. The most likely case for doing this is if you need to reinstall the Peercoin client on a new computer, or after you've had to format the disk due to an unrelated issue. In that case, you'd install the Peercoin client (ppcoin-qt) per the current instructions and launch it to make sure it's working correctly. It WILL NOT contain your account balance, so don't worry -- that's what the next steps are for.
The most straight-forward way to do it is to use the OSX Terminal application to access the system's command line interface. I've covered it in the Mac PoS tutorial, but for a quick primer, it's located in Applications > Utilities > Terminal.
Once Terminal is running, insert your USB into your Mac, and copy and paste the [font=courier]wallet.dat[/font] file that you backed up on to your desktop. By copying and pasting, rather than dragging it over, you can maintain that copy on the USB, in case anything goes wrong.
: I'm using the file name [font=courier]wallet.dat[/font] for simplicity, but you may have renamed it. If you did, just replace that name when you see "wallet.dat" referenced in the instructions.
Next, in Terminal, type the following (and remember, "$" is not included in the text you need to copy, it's just there to indicate where the prompt starts):
$ cd ~/Desktop/
What that did was to set your context to your Desktop directory and then display a list of all the files and directories stored in it. You should see a listing for [font=courier]wallet.dat[/font]. If you do, we're ready to go on to the next step; removing the default wallet file and then moving the backup into the ~/Library/Application\ Support/PPCoin/ directory.
$ cd ~/Library/Application\ Support/PPCoin/
$ rm wallet.dat
When the directory contents are displayed using the "ls" command, you should no longer see a [font=courier]wallet.dat[/font] file listed. Next we'll use the "mv" (move) command to pull the file that we put on the Desktop over to the ../PPCoin/ directory:
$ mv ~/Desktop/wallet.dat wallet.dat
Listing the directory contents should now show a [font=courier]wallet.dat[/font] file.
Start up PPCoin-Qt and let the blockchain synch. Once the client has caught up to the most recent transactions, you'll be able to confirm you're using your backed up wallet, and any transactions that occurred since the backup happened should be reconciled with the blockchain synch.
And then you're ready to get back to whatever you were doing before you had to reinstall.
ALL: Can I get a quick proofread of the steps? I think I got them correct, but just in case I missed anything fundamental, I'd like a review. Thanks!