Hello, I am trying to figure out how to take my current SCCM configuration and have it manage other domains also, opposed to the one domain that it is joined to currently. Do I create a secondary site? Any information would be greatly appreciated.

By domains, do you mean multiple domains in the same forest, or different forests? It makes a little difference as to the answer :-) Whenever I refer to domains, it means a single forest in my answer below. A single primary site can manage clients in multiple domains, no issues at all. You may need to add a Network Access Account to your site, depending on trust relationships (but with multiple domains, I'd always create one). The docs very clearly discuss this account and what it is used for (please look at the docs for this). A single primary site can also manage clients in a remote forest, but the clients in the remote forest can't access site objects in AD of the site server's forest, so you need so.me method of finding the site code (an SLP) and MP. That can be WINS or DNS. A hierachy can span forests if using primary sites. Secondary sites must be in the same forest as the parent primary site.

Thank you for the response, is it possible to do this without a WINS server?

As I mentioned in the response, you could use DNS if you have a common DNS between the forests and you enable DNS publishing (not done by default). Otherwise WINS (or LMHOSTS files).

If I were to add a second domain (child domains under the same forest) would I add them via network discovery properties or will it pull automatically with the forest being referenced in the discovery by ad???? Thanks