What is the ruling on my explaining an American e-bank (PayPal) and the methods of dealing and purchasing through it? And am I sinful for that?

There is no harm in permissible dealings with the PayPal website, nor in explaining how to register and deal with it. Whoever deals with it must avoid forbidden things. If one commits a prohibited act, the sin is upon him, for Allah Almighty says: "And no bearer of burdens will bear the burden of another."