I download the open office 2.2 but I don't know how can I unpack the tar file. I hope someone can help me.

On the commandline, do:Replace <package-name> with... the name of the package It creates a directory, enter it with the cd command: cd <directory-name> and doIf this command sequence fails, do it again as root.

I think joe108 downloaded the binary tarball. In which case follow the instructions here. Even better use Debian's openoffice, you are far less likely to run into problems.

On the other hand, if you are compiling openoffice, Dutch Master's method doesn't quite cover it unfortunately.
It is quite a bit more involved than the usual ./configure && make && make install (99% of programs can be compiled this way, so don't let this post put you off compiling in the future which every linux user should do at least once IMO).

If you are intent on compiling from source
a) Buy a supercomputer, openoffice takes a ridiculously long time to compile, and
b) use the BLFS instructions as a starting point. When I last compiled it, (first and last, I might add) I had to tweak the instructions slightly to get it the way I wanted. This meant I had to build it twice (5 days of my life I'll never get back, sigh).