Dev-libreoffice installation: how to?

I am using Ubuntu 14.04 and LibreOffice 4.2.5.

I would like to play with source code of libreoffice but I am not familiar with the way you change the source code and then build new version. Also, I am not familiar with possibilities to install both Stable (4.2.5) and Development version at the same time in Ubuntu? However, I am familiar with C++ and programming in general.

So, how can I use stable 4.2.5. while at the same time have posibility to play with source code and build new verison under Ubuntu 14.04? thanks

Refer to the Development section of the LO website. There should be links to detailed instructions on TDF wiki. Downloading the source code is done via git and this (with the tools to build LO) do not interfere with any installed version.