Step I : Download and Installation
IF you have full installation of Fedora Core 3 then you have ht://Dig installed.
Check whether you have htDig installed or not by:
#rpm -qa | grep htdig

if you get a package then it is installed else

download it from here:
http://www.htdig.org/files/htdig-3.1.6.tar.gz
and
Install it using following:
#tar zxvf htdig-3.1.6.tar.gz
#cd htdig-3.1.6
#./configure
#make depend
#make
#make install

This will install htdig,htfuzzy,htmerge,htnotify commands specified by BIN_DIR in CONFIG file.
In my fedora core 3 setup I have these executables in /usr/bin.
Check out for your installation by:
#rpm -ql htdig-web

Step II : Minimum Configuration
#vi /etc/htdig/htdig.conf
Go to line stating start_url and change http://localhost to your website name.
Exit vi editor.

#rundig
This may take several minutes accroding to your site.

#mkdir /var/www/html/htdig
#cp -rv /usr/share/htdit/* /var/www/html/htdig/
This will copy all needed files to htdig directory in your apache web servers root directory.

#service httpd restart
Not needed necessarily.

Step III : Testing
Go to Web Browser.
type http://localhost/htdig
You will have an html page with search option.
Choose options accroding to your needs.
Enter keyword to search from your web site.
You will get result.
Enjoy search engine for your website.

Reference : http://www.htdig.org