if i want to disallow incoming HTTP connections using IP tables, please which commands i need to use?

I tried
iptables -A INPUT -p tcp --dport 80 -j DROP
but it still load the website..
how then i can remove that rule? Exactly same command only with -D ?

EDIT: I found the answer, iptables -A means it will append rule to the end of rules list, when i inserted it at the beginning by command iptables -I , it worked.

Command to add:
/sbin/iptables -I INPUT -p tcp --dport PORTNUMBERORNAME -j DROP

Command to delete:
/sbin/iptables -D INPUT -p tcp --dport PORTNUMBERORNAME -j DROP

to get list of open ports: nmap localhost

For rules to survive reboot, on Debian I did: sudo iptables-save|tee -a /etc/iptables/rules.v4 && sudo iptables-save|tee -a /etc/iptables/rules.v6

if you want to allow/deny port connections repeatedly, you may use my script to simplify the job.