Hello Pippa. I'm sorry you're feeling so frustrated, Let me try to help. I'm just a user, not a member of the team, but I've been using Scrivener for over 10 years.
The first thing to understand is that although, on your desktop, a Scrivener project looks like a file such as one created by Pages, it is actually vastly different and hidden behind what you see may be hundreds—or even thousands in a big project— of files all linked together. You don't need to worry about that, but just realise that sync'ing a Pages file is very easy compared with sync'ing a Scrivener project.
Secondly, while you can save your Scrivener project to iCloud and access it on different devices, a lot of us would say "Don't!" because it is a greater risk of corrupting the structure than Dropbox, because it is slower and it's not so easy to see when the project is fully uploaded to the server or downloaded to your machine. The upload must be complete before you shut down a machine on which you have been working, and the download must be complete before you try to open the project on a given machine. Also, funnily enough, even though the iPad is an Apple device, because of the way iOS works, apps like Scrivener are sandboxed which means they can't read data from other applications and, as I understand it, Apple doesn't provide developers with the necessary code to sync data backwards and forwards easily between "Files" and other Apps like Scrivener. Dropbox does provide the necessary code which has allowed KB to do it.
So, you need to use Dropbox for that purpose, though you can do it with iTunes—someone else will have to give you a heads-up on that … I've never tried so don't feel competent to advise. On the other hand, Dropbox, once you've got it set up right is pretty easy. Assuming you already have a Dropbox account:
1) Download the Dropbox app
onto your iMac—it doesn't work through the Dropbox web interface— and log it in to your Dropbox account. It will set up a "Dropbox" folder in your user area on the iMac.
2) Open that and check if there is an "Apps" folder within it and create one if there isn't.
3) Open the "Apps" folder and create one called "Scrivener".
4) Move your Scrivener project into that "Scrivener" folder within the "Apps" folder within the "Dropbox" folder. It should look something like this:
On your menu-bar at the top of your screen you'll see a new icon of five black diamonds round a white one … it resembles an open cardboard box. It should also have a little disc at the bottom right with rotating arrows or something; that tells you Dropbox is in the process of sync'ing. You must
wait until that "badge" goes away, indicating that Dropbox is fully sync'ed. It may take some time the first time you do it … you can check on how it's going by clicking on the Dropbox icon and it tells you at the bottom of the menu that drops down.
5) Now, on your iPad, install the Dropbox app from the App Store.
6) Open Scrivener on your iPad; I would have the iPad in landscape orientation … I think it makes it easier to see where you are. At this point, I would open the Tutorial : Draft and choose the "Syncing" card. That tells you exactly how to proceed from here.
Just in general, I don't know if you have done so, but you will save yourself a lot of heartache and wasted time by spending an hour or so going through the Tutorial you find under the "Help" menu on your iMac, and the whole of the iPad tutorial. It will help you to understand how different Scrivener is from Pages, and also what things are called in the Scrivener interface. That will make it easier when/if you come back for more help and advice.
Good luck. Get back to us if you're still having problems, and persevere … you'll find that you've made a good choice.