Public Apache Web Server on Raspberry PI

I would like to host a PUBLIC apache web server on my Raspberry Pi running Apache2 installed. I would like to point my current domain at it, but the "public ip" of the server doesn't load the apache server? I have done all the port forwarding?

Can anyone take me through in steps explaining how I can do the sentence in bold.

Thank you - I do need to know very soon however, sorry for the rush.