installing deb files
I downloaded mercury-messenger-1.9.5.deb package and tried
to install it using the following command : sudo dpkg -i mercury-messenger-1.9.5.deb
after that i got this message :

(Reading database ... 102942 files and directories currently installed.)
Preparing to replace mercury-messenger 1.9.5 (using mercury-messenger-1.9.5.deb) ...
Unpacking replacement mercury-messenger ...
Setting up mercury-messenger (1.9.5) ...

it seems that every thing goes will !,but i didn't found the program in the application menu ,RealPlayer11GOLD package has the same problem ,want some help !

In a terminal type
You need to create the entry in the menu yourself.
idem for RealPlayer11GOLD

OK ,every thing went well ,when i opened /usr/share/mercury directory i found this subdirectory :

jni lib resources startup

under startup Dir. there's startup_linux.sh file ....what should i do now ?

to start mercury, type
or
/bin contains the program executables.
/share contains the conf files etc

OK ,every thing went well ,when i opened /usr/share/mercury directory i found this subdirectory :

jni lib resources startup

under startup Dir. there's startup_linux.sh file ....what should i do now ?

did you do what I suggested?

sorry ,i just hit the submit replay button twice time,
the following message appears when i wrote mercury in the shell :

- Adding Compiz/beryl compatibility mode.
/usr/bin/mercury: line 43: java: command not found

You need to install java

Use the packet manager to do so
Take a look at
http://mediakey.dk/~cc/howto-install...n-debian-etch/