Im totally new to Linux in general so if this isnt what you mean, Im
sorry.

If you know the name of what you are wanting, like SciTE, then by typing
sudo (superuser do) apt-get install scite that would install scite.
That is all you have to do really. Its pretty cool -esp coming from
windows. The service finds the software, installs it, places a icon in
the applications menu and thats it.

As for deb, to do .deb files read this on the Unofficial Ubunto 5.04
Guide: www.ubuntuguide.org/#installuninstalldebfiles