Block all web access and whitelist with openwrt

Sorry for posting about openwrt on the lede forum, The openwrt forum is down but mentioned this forum as a possible source of info, I have a TP Link 1750 Running Chaos Calmer 15.05.1 / LuCI.

I want to block all Sites and IP addresses that devices connected to the router can connect to and then whitelist a few Sites / IP's of my choosing, I've been informed that this can do this with Iptables but I'm new to all of this and my attempts so far haven't gone to well,

one mistake I made in "Network > Firewall > Zones > Lan".... I changed Input Output and Forward all to "Drop" and was no loner able to log back into the router, Had to reflash via ssh.. lesson learned lol.
Everything is back to default settings now.