I am not sure I clearly understand the question but:
- If what you want is solely to keep safe a copy of your book in its current state, simply do as @kewms said. Use
File / Backup / Backup To and store that backup somewhere secure.
I recommend that you then have Scrivener zip and timestamp this backup in the options:
- You can also use
File / Save As to create a new “live” version of your project, with a different name, in a new location. (If the idea is to have that new version on a different computer, generate the new copy from the computer on which the source project currently reside, and transfer that new version afterwards (use a thumbdrive for e.g. – or zip and email the new project folder to yourself).) Make sure the new version has a name that can’t be confused with the name of the original/source project.
Avoid leaving residual duplicates behind. (As a general rule: duplicates are never (or very very rarely) a good idea.)
Before doing anything, the priority should be to make sure you’ve got your project properly backed up somewhere. (Except in the case of the first possibility, where creating a backup is the whole of the idea. Just create a backup in that case, and that’s it, your done.)
Myself, when I want to create a “mile stone” copy of my project, I just have Scrivener create a zipped and timestamped backup copy, and that’s it. I upload it somewhere safe with all the others (the timestamp making them easy to tell apart) and I’m done. I can move on.
Once you’ve done a backup, if you still want to rename your project (say from “projectname_firstdraft” to “projectname_seconddraft”), you should be able to simply close Scrivener, and rename that project from within whatever is the Mac equivalent of Windows File Explorer. (That’ll leave you with only one “live” version of your project – which is ideal if one live/current version is all you need. You’ll be working on the original, under a new name. The zipped backup making sure you can still go back to your project in the state it was in at the time (so today), if need be.
→ I won’t say more as to how specifically to manually rename a project, I ain’t a Mac user. I’ll leave that to someone who’s actually using the same OS as you.
Again, whatever you do, if it involves moving or renaming a project, first make sure you have a backup safe somewhere. (It is normally not something to worry about for such a minor operation, but better safe than sorry – especially if you are not fully comfortable with what you are doing.)
P.S. I included instructions for the case where you’d have two computers because:
You said that your project is on your desktop.
If by that you meant “desktop computer”, the fact that you mention it implies that is involved a second one (such as a laptop).
If that is not the case, just ignore whatever I said that pertains to that hypothetical second computer.
You might also be into learning about snapshots if you haven’t already, as they allow to keep versions of your documents inside a single project, namable if you wish (“first draft”, “second draft”, whatever you’d like) and easily recallable for reference. They don’t replace proper backups though. They are just an alternative way of achieving what I think you want to do, but conveniently within a single project.
(Plus, in that optic, you don’t have to wait to be done with your whole manuscript to declare that a chapter is now a second draft. Your project can evolve freely, so to say. You can use that in combination with the status (sort of a second label) of documents.)