Q: How I can print a ebook I did purchase in itunes? So far I only can "read" on my ipad trough ibook app? I don't see the print option. Or how I can save it as a PDF so I can read it on my imac and macbook?

Unless your iMac or your MacBook is running OS X Mavericks (10.9) then you can only read them on your iOS devices due to the fact that they are in DRM protected form.

Apple has add iBooks to Mac via Mavericks. The upgrade is free if your machine meets the requirements:

To install Mavericks, you need one of these Macs:

iMac (Mid-2007 or later)

MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later)

MacBook Pro (13-inch, Mid-2009 or later),

MacBook Pro (15-inch or 17-inch, Mid/Late 2007 or later)

MacBook Air (Late 2008 or later)

Mac mini (Early 2009 or later)

Mac Pro (Early 2008 or later)

Xserve (Early 2009)

Your Mac also needs:

OS X Mountain Lion, Lion, or Snow Leopard v10.6.8 already installed

2 GB or more of memory

8 GB or more of available space

Most DRM protected eBooks will not allow you to print them to paper, if that is what you mean.

As Axeman already said, if you update OS X to Mavericks, you can read them in iBooks for OS X.

There is no way to convert them to another format either (not legally at least - again, the DRM is intended to prevent that).

Any DRM protected eBook purchased through iTunes will only be readable in iBooks - you cannot authorize them to read in other ereaders (say, via Adobe Digital Rights Management software).