There are many tools one can use for content analysis, one of which is the open-source AmCAT. Easy enough, a server is running at http://amcat.vu.nl/ where new projects can be set up. Like other content analysis systems, AmCAT can be a bit confusing when you first use it. I recommend a look at the manual, and especially the hands-on guide (because the manual isn’t always so clear). If you want to link AmCAT with R, have a look and the second hands-on guide. Once the basic setup of AmCAT is clear, coding is straight forward.