How to analysis large sum of sequences ? - Blast program write by myself ? is it possible ? (Mar/06/2002 )

If I have large sum of DNA sequence, I would like to generate somethings just like blast program to search among the large sum of DNA sequence. How can I do that ? Is there any books or papers talk about how to do that ? thx a lot

"database"? or another command in GCG can create a database from your sequences then you can search the database by blast or other search engines...