How to install ".tar.bz" files

[Thomas Blasejewicz]

Please enlighten me as to how - if possible - SIMPLY install compressed
files.

What I want to do:
Install "OmegaT" (a tool to assist translation).
Synaptic or the "Software Center" do offer an installation, but they
will install an outdated version.

So, I downloaded the newest version of the software as a compressed
file, called:
OmegaT_2.0.5_02_Linux.tar.bz2.

If I right-click or double click on that file, Archive manager opens and
allows to unpack it.
Fine.
Otherwise the file just sits there and does nothing. Neither can the
application be launched.
The readme file says:
* Others: To install OmegaT, simply create a suitable folder for OmegaT
(e.g., /usr/local/lib on Linux). Copy the OmegaT zip or tar.gz archive
to this folder and unpack it there."

I cannot copy or move that file. I always get an error telling me
"Permissions denied"; both with the compressed file and an unpacked
folder. Why is this necessary? I have administrator rights on this machine.
I created a folder within my home folder to put the downloaded file and
unpacked it there. That means, I could/can copy/move this file around
elsewhere.

AND
"3.3 Launching OmegaT
* By double-clicking on the file OmegaT.jar. This will work only if the
.jar file type is associated with Java on your system.
* From the command line. The command to launch OmegaT is:
cd <folder where the file OmegaT.jar is located>
<name and path of the Java executable file> -jar OmegaT.jar"

Neither of these seem to work.
Is it absolutely necessary to have these files in /usr/local/lib on Linux?

So, is there an easy (like "click install") way of installing THIS (or
all other similar) file?
Preferrably having to resort to numerous, complicated commands?

Reading through the documentation and googling has brought up only very
specific instructions for particular software.
And ALL require of lots of commands.

Thank you.