The instructions on installing Oracle depend on what OS you plan on installing on. There are minimum OS patch levels, with unix you need to set the semiphores properly and create an oracle user and DBA group. Fortunately Oracle wrote those for us.

Windows version:
http://download.oracle.com/docs/html/A95493_01/toc.htm

Unix/Linux version:
http://download.oracle.com/docs/html/A96167_01/toc.htm

Also you should post things in the right forum.