Zaps are Bitcoin Lightning payments.  You'll need a Lightning Wallet to send or receive Zaps on nostr.  Wallet of Satoshi is probably your best bet for a newbie friendly wallet everywhere except the US.   If you're in the US you should use GetAlby or Strike.  GetAlby has a waiting list, but Strike has KYC, so take your pick... 

As for relays, use your client's default list for now.  As you find users you like, you can look at their relay list to add some of the other popular ones, but try to keep it under 20 relays for performance sake.