How to: Convert PDF Files To iBooks [Windows-Mac]

How many of you know  that iBooks is not just an eBook reader but also a PDF viewer that lets you open and read a document saved in this format. But it is not the best way to read your PDF files, so I will show you today a guide of how to convert PDF eBooks into iBooks compatible books.
Steps:
Step 1: Download and install the Calibre application on your computer from here.[For both Mac and Windows]
Step 2: Install Calibre then run it, you will be greeted by a screen configuration wizard, Select the directory where will eBooks files saved after it converted, then click "Next".

Step 3: Now you must choose "Apple" from the list of producers and "iPhone / iTouch + Room" from the list of devices. then click "Next" and the installiation is complete.

Step 4: Now click on "Add books" and select the PDF you want to convert.

Step 5: Once your PDF has been added,  you can add  details such as title, auther, cover, ... etc. (this is optionaly)
Step 6: Once finished editing, click on "convert books" and then confirm the operation.

Step 7: Once your PDF has been converted, head over to the folder you selected to save converted file in (Step 2) then drag the converted book (it should be a .ePUB file) into your iTunes library.

Step 8:Finally connect your iPhone to your computer and synchronize with iTunes. The book will be automatically copied to iBooks with its new design.

Here is the two screen-shots showing the Books before and after conversion:
Before:

After:

Note: the guide was performed on Windows, but Mac users should have no problems to follow the same procedure too.