You'll have access to all kinds of tools for this type of drawing. You'll be able to create not only flow charts, but also UML diagrams, electrical circuits and networks, timetables, maps... Any design can be shown after downloading Dia for free, because it has been developed under the GNU license.
The resulting files will be saved as XML, a format that's compatible with many other applications, in such a way that you'll be able to combine the work between them. You'll also have the possibility to export your work as EPS, SVG, CGM, PNG or the program's own format.
The program is easy to use and if you're a newbie you shouldn't have any problem, because it's very easy to understand. Start creating your own diagrams thanks to the powerful free tools provided by Dia.