These are general instructions for any ereader device that supports Adobe DRM. Common devices are Nook, Kobo and Sony Reader, but there are hundreds of others.
If you are not sure if your device is supported please check here. Even if your device is not listed here, if it says on it's packaging that it supports Adobe DRM or Adobe PDFs / Adobe EPUBs then it should still work.
Before we get started you need to have completed the following steps:
Once you have completed these steps you should be able to transfer your ebook fairly easily. Simply open the Adobe Digital Editions software on your computer and make sure it is on the Bookshelf screen.
Then power on your ereader and plug it in to your computer (please do not plug it in to a USB hub).
Your ereader should then show up in your ADE bookshelf as a device. You can now drag and drop the ebook you wish to transfer on to your device to begin transfer.
If you have not authorised both Adobe Digital Editions and your ereader device, or if you downloaded your ebook file before you authorised Adobe Digital Editions then you may receive the CE_COPY_NOT_ALLOWED error.
Please note that if you are using Linux then things will be more complicated as you need to run ADE using Wine. For more information see this article.