Nope, no port 80, which tells you that it is blocked
The normal way of setting up iptables is to 'block everything unless stated different'. You do not have a rule that allows incomming traffic on port 80, so it is blocked.
Your next question might be "How do I add this rule?"
There are many ways to set up an iptables firewall, so the following might not work for you:
iptables -A INPUT -p tcp -i ppp0 -d 1.2.3.4 --dport http -m state --state NEW -j ACCEPT
1.2.3.4 being the IP address that you ISP gave you.
If you enter this from the commandline, the rule will be lost after the next reboot. Find the script/config file that is used by iptables on startup and add it there after you confirmed this will work for you.