Install WebSphere Portal Server from the IBM installation media. The default installation is used, without any configuration changes. There is a link to the Websphere Portal Server documentation on the first screen of the installer, follow that link to find out more information about installation requirements and instructions.
On one of the installation screens there is an option to enable services to stop, start, and perform recovery actions for your server. This is an optional step but is not recommended as this has not been tested.
You should not install WebSphere Portal Server to a directory that contains spaces in the name, i.e. the Program Files directory.