everything is in the wiki and in books :)

Static scenarios with some basic database lookup can be done in XML:

https://wiki.freeswitch.org/wiki/IVR_Menu

More complex IVR can be programmed in Lua, Javascript, Perl,...

http://wiki.freeswitch.org/wiki/Examples_ivrmenu_js

https://wiki.freeswitch.org/wiki/Lua_Welcome_IVR_Example

And, before you go any deeper, you will need to read the book:

http://www.packtpub.com/freeswitch-1-2/book

From: Roman Gelfand <rgelfand2@gmail.com>
To: FreeSWITCH Users Help <freeswitch-users@lists.freeswitch.org>
Sent: Monday, October 28, 2013 1:54 AM
Subject: [Freeswitch-users] ivr application

I am new to freeswitch and would like to develop an ivr application.
I understand there are many ivr freeswitch-based platforms. Could you
point me to the most widely used? Coding examples,etc...?

Thanks in advance