Buying a domain in use

I want to buy a domain that is in use. When I search on whois it says the administrative and technical contact is gateway@gateway.com. Somehow, I doubt that I’m going to get a hold of this person.

However, if I do. How should I go about purchasing the domain from him?

Thank you,

I recommend buy or (and) sell your domain names only through trusted marketplaces such as SEDO or namepros.

Well you ask if the owner is willing to part with the domain and sell it to you.
Otherwise…you won’t be able to have it.

the domain in the email address gateway.com is the domain for the Gateway computer manufacturer (a competitor to Dell, which was fairly popular 10-12 years ago.)

I very much doubt the company will let go of a domain.