Ubuntu uses apt-get.
You should head over to the Ubuntu forum on this site and read the stickys. You can use this site as well for referencing package names: http://packages.ubuntu.com/
It's hard to say what package you need from your description, buy the basics of the command are:
sudo apt-get install packagename
If there isn't a "ubuntu package" for what you need you can try a .deb and install with dpkg.
The ubuntuguide in the sticky has directions on all the stuff a new person will need and with basic package installations like you're looking for. I think easyubuntu and synaptic will probably help the most for you. The synaptic program has a GUI and will let you install a lot just by clicking the name of the program. I think another good one is Automatix.