How do you get started organizing a class?
How do you take the absent students names?


I don't.  If a student finds my lectures boring or useless, they shouldn't waste their time coming to class.  (As others point out, there are very good reasons to require attendance in laboratory-, studio-, and discussion-based classes.)


  How do prepare your materials?


Coffee and LaTeX.  Lots of coffee and LaTeX.


  How do you write a syllabus for students and do you hand them out?


When I started out, I modified the syllabus from the previous iteration of the course, which was taught by an experienced instructor, so I could be sure to include all the necessary details.  I used to hand out the syllabus on the first day of class, but now I just post it on the well-advertised course web site.


  What computer programs do you use to plan your lessons?


I write everything in LaTeX (specifically, TeXShop) and distribute everything as PDF files on the course web site.  (See the first question.)  I also use SubEthaEdit to edit the course web pages themselves.