How to install software in Linux ?
 

I am using Fedora 18.
Please explain me how to install software in Linux ?
Please explain me how to install C/C++ compiler in Linux ?

not sure about a gui, but the command to install software is 'yum'
or more precisely
su -c 'yum install {package}'
enter root password
hit y when prompted, or to skip the answer y part the command is
su -c 'yum -y install {package}'
enter root password

note you should also run
su -c 'yum update' periodically as this keeps your system up to date with the latest versions of installed packages.

These webpages might help:

https://ask.fedoraproject.org/questi...ular-software/
http://docs.fedoraproject.org/en-US/..._Software.html

Hi and welcome to LQ!
Fedora uses yum as package manager. Here a guide.
For c/c++ compiler it could be already installed. You can verify it with: which gcc
If no, you can installed it with: yum -y install gcc gcc-c++