I suppose you have made the forms with 9i designer and / or developer.
If you only want to run the forms locally in your browser, there's no need for 9iAS. You can use the OC4J instance, installed with 9i Designer/developer. It can be found in forms developer folder using the startmenu. It starts a command box, don't close that one.
For designer additional settings have to be made to run the form directly after generation. Using developer it should be doing great.
If you want to deploy the forms on the web, you'll need the 9iAS. For setting that one up, please refer to the online documentation shipped with 9iAS and / or look in http://technet.oracle.com.
Edwin van Hattem
OCP DBA / System analyst