Just try out this.....
Open Gedit and click edit > preferences > view > bracket Matching > highlight matching bracket
next edit > preferences > editor > tab width 4 (u can change it)
next edit > preferences > editor > automatic Indentation > enable automatic indentation
and lastly, edit > preferences > syntax highlighting > highlight mode > C++

See here and dnld as ur requirements: http://packages.ubuntu.com/lucid/i386/gedit-plugins/download
and this is here also : ftp://ftp.gnome.org/pub/gnome/sources/gedit-plugins/2.15/

To install either use apt-get or synaptic package manager

Doing code in C I'd recommend Geanie if you want a very light IDE, if you'll settle for one to make things easy. Otherwise slightly larger but still light is CodeBlocks, which has a constantly updated and maintained windows and linux version. I run it on both my systems (Laptop and Desktop) which are both dual boot systems, Kubuntu 12.04 and Windows 7 Home/Pro.

Both can be found in the Ubuntu Software center, Otherwise google it. They truly are great programs.

Extremely sorry for my late response! which version u r using gedit, while my ver is 2.12.1, where I easily found edit > preferences > syntax highlighting > highlight mode > C. Plz check it.