Providing you have the licensing, you would have to download the additional poller package to the server that would act as a secondary poller. This is a relatively large package (about 1.5 - 2.0 GB). You would then need to install the package and run the configuration. It is relatively straightforward, if I understand your needs correctly (adding an additional poller to an existing Solarwinds environment, not actually setting up another Solarwinds environment).
you must either have the same version on the primary server, and the same modules. No link to download this tool to test.
My suggestion is to upgrade to the latest version of all modules you have in your main servirdor and talk to the sales staff of SW