Ipad air

Hi, Just bought the latest iPad Air, which goes nicely with my iPhone and the latest iMac. Obviously I have linked them all via iCloud and photo,s etc are linked to all devices.
But I have lots of downloaded books on my iMac which I cannot seem to transfer across or share with my iPad. They were not bought via iTunes as I am not sure if they have to be before you can transfer them to your other devices.
But I have downloaded music from other sources and they transfer nicely from one device to the other.
Can anyone help me to solve this conundrum please ?

But I have lots of downloaded books on my iMac which I cannot seem to transfer across or share with my iPad.

Click to expand...

What kind of downloaded books do you have? For example: I have a library of Kindle books on my iMac which I access with the free Kindle reader for the Mac. However, in order to read those books on my iPad I would have to download the free Mobile Kindle reader for the iPad and iPhone.

Unfortunately I have no idea, they were from a free site and i can get no information by right clicking or any other way.
Sorry.

Solved my problem, thanks for the help.