To transform dita files to a publishable output, such as XHTML or PDF, we need to run ANT builds, and we do it through the DOS command line. Another option is to use a GUI. I find the WinAntEchidna GUI, developed by HyperText, to be very handy.
The first time that you use WinAntEchidna, it asks you for the installation directory of the DITA OT (this, like all parameters, can be changed any time). Thereafter, every time you run WinAntEchidna, all you need to do is specify your ditamap file, your output folder, and your output type.
WinAntEchidna can be downloaded from http://sourceforge.net/projects/winant-echidna/.