John, Specific questions are much more appropriate than broad questions. Remember that everyone who responds is volunteering their time to help you. Please respect their time by only asking those questions that cannot be answered by a few minutes worth of research using Google or your favorite search engine.
Is 100% Perl written?
No. As you can see from the ohloh page, Koha also includes SQL, Javascript, and XSLT: http://www.ohloh.net/p/koha
how many types of archives exists? what the system will do when operational?\
I don't know what you mean by this. If you mean how many types of libraries are there, the answer is "indeterminate, but lots." The manual at http://koha-community.org/documentation/ provides detailed information about what Koha does. How it works inside the client and server? at glace of course.
Koha is web-based. There is a LAMP server with a Zebra or Solr indexing engine, and users connect via a web browser. if there are a sketch will be nice,
There is not one, so far as I know. Regards, Jared -- Jared Camins-Esakov Bibliographer, C & P Bibliography Services, LLC (phone) +1 (917) 727-3445 (e-mail) jcamins@cpbibliography.com (web) http://www.cpbibliography.com/