If you could let me know what you’re searching for I can take a closer look, but essentially on the search page the fastest way to locate a community on another server is to type the url of that community (for example, https://mtgzone.com/c/mtg) or it’s Lemmy address (!mtg@mtgzone.com).
I’ll write up a getting started guide as well on this and searching/connecting/interacting with other Lemmy websites.