After installing ArcIMS, you must create virtual directories for Manager, output, and website. A virtual directory is a mapped location on the Web server to a physical path on the hard drive.
Note: If you browsed to the location of your Web server root directory to create directories for output and website (the Web Site Working Directories) during ArcIMS installation, you don't need to create virtual directories for output and website (you can skip this step).

a. Stop the Apache Web Server.

b. Make a copy of Apache's configuration file (httpd.conf) and name the copy:
httpd.conf.before_ArcIMS

c. Open
\Program Files\ArcGIS\ArcIMS\Common\ApacheAlias.txt
in a plain text editor and copy the contents of the file to your clipboard.
Then close the file.

d. Open
\<Apache_Home>\conf\httpd.conf
in a plain text editor. Under the line which reads:
Alias /icons/ "<drive>:/Program Files/Apache Group/Apache/icons/"

paste in all the lines you copied from the ApacheAlias.txt file.
Note: Replace the paths in these lines with the appropriate paths where necessary.

e. Save and close the httpd.conf file.

f. Start the Apache Web Server.

See "Step 5: Configure ArcIMS" in the ArcIMS 4.0 Installation Guide for the final step required to get ArcIMS running.