There are a few ways to search for a website related to your topic.
Google - search for a couple of topic words and look for organizations and associations related to the topic. Or use the Advanced Search and use the domain field to search for .edu, .org, or .gov.
Wikipedia - Look at the External Links for suggestions. Don't use the Wikipedia site for a source!
Don't forget to evaluate the website before using it as a source.
Before you use a website, make sure it's authoritative, credible, and current.
Authoritative
Credible
Current