have You been scammed by someone who is using an website to commit fraud/scam?

You can try to collect evidence like screenshots, emails, date/time information and report this illegal activity

1) You can check who is the website owner

Go to http://google.com and search for "whois check", enter some of the found websites. Then on the whois website, enter domain name of the scam/fraud/fake website (example: domain.com)
this way, you should be able to see who is the owner of the domain. The data can be faked of course. Take a note that it can be illegal to publish any private data of someone.

2) You can discover which company is hosting the website

To discover hosting of some website (where the website data are located), go to http://google.com and search for "check hosting of a domain". Enter some webpages that has been found and add the bad domain to get some details about IPs/hosting company behind the site. Google websites that allow you to input IP of bad website and they will return more details about IP, usually you find provider of that IP network. Im using http://myip.ms for this. Then contact the hosting company. It is possible that if You give them evidence of the criminal activity, they will suspend the site. Require response, be polite, track the case.

3) Discover domain registar and report the domain to them

please use an whois website mentioned in step 1 to discover whois details of bad domain name. You might be able to find the domain registar and contact them sending them evidence regarding fraud. Sample whois lines we are looking for are below. In this example case, .com domain whois:

[Querying whois.verisign-grs.com]
[Redirected to whois.godaddy.com]
[Querying whois.godaddy.com]
Domain Name: xyxyxy.com

In above case top level domain authority is verisign and domain registar is godaddy. I would report to domain registar (Godaddy in this example case).

4) share Your experience/review in pubic

You can use forums, discussions or private website to share your experience with bad/fake/fraud website. You may use search engine like Google and search bad domain name. This way, you find webpages that talks about the bad service, so this is a good place to add your "review"/experience. Do not reveal any private information of the possible website/service provider/owner as usually anyone has right for their private data not to be dirtied publicly.

5) report the case to the police

In case you are sure that the person who commited crime is doing so from same country like yours and you know you have evidence that is suffficing for proving the crime, report the crime to the local police.

6) learn from it and move on
it is not good for health to keep feeling bad, forgive