It’s not possible via web UI as you can only choose TCP or UDP but you’ll need ICMP protocol. You can realize this with a custom template:
mkdir -p /etc/e-smith/templates-custom/etc/shorewall/rules/
/etc/e-smith/templates-custom/etc/shorewall/rules/91ping with following content:
Ping(ACCEPT) loc net
Expand the template and restart firewall:
Now ping from LAN to WWW should work.