The file extension means nothing in linux, they're there for the user's benefit. Even if you called a .tar.bz2 file .zip you could untar it using:
tar jxvf filename.zip
as if you'd never renamed it.
Anyway, I'm not sure why you're having such problems. If you've downloaded a file ending in tar then:
will untar it. If it ends in .tar.gz (or .tgz) then:
Code:
tar zxvf myfile.tar.gz
will untar it. If it ends in .tar.bz2 then:
Code:
tar jxvf myfile.tar.bz2
will untar it. Then, assuming you've downloaded source code, you would:
where mynewdirectory is the directory created when you untarred the tarball.
And then read the README or INSTALL file, which usually tells you to:
Code:
./configure
make
(become root - by typing su and entering the password)
make install
(to put the program on the system at large)