There IS free webhosts, like 000webhost.com and if you want to host your website through your External IP (Not the one who starts with something like 192.168.xxx.xxx) then you should portforward Port TCP/UDP 80. Then it will work once you have portforwarded that port. You will need to give your external ip to the people you want to join your retro, and if it's too hard to remember, try this service :
You must be registered for see links
You can get a subdomain like (Yourhotelname).no-ip.info . The website will still be hosted in your computer, the subdomain is just hosting your External IP Number. If you want to check if you correctly forwarded port 80 (HTTP) then you should go to this website
You must be registered for see links
and type in the port to see if it's open.
Thanks hope this helped! READ THIS POST IT WILL HELP YOU OUT