Welcome to LQ. .. ..
... And when you have read everything in the two links from @fbobraga:
Command line : Open a terminal window and try this :
apt-cache search <name> ( or part of name ) : To find a package.
sudo apt-get install <package-name> : Will install a package.
We do not download software for Linux.
The selection of 30,000 packages covers the most basic stuff.
Here you have an overview of the packages :