Is it permissible to open a religious page on Facebook as an ongoing charity (Sadaqa Jariyah), and is it necessary to announce that it is an ongoing charity?

"Ongoing charity" (ṣadaqah jāriyah) is understood by most scholars to mean an endowment (waqf). For it to be considered "ongoing," its principal must remain intact. The majority of scholars do not permit the endowment of usufruct (manfa'ah) and stipulate that the endowment must be perpetual. Accordingly, if a page serves as a means for teaching beneficial knowledge, its owner will receive its reward as long as the effect of this knowledge remains. It is not a condition for this reward to be obtained that the page explicitly declares itself as charity; good intention suffices, along with the beneficial knowledge and sound admonitions that its visitors gain from it.