I see that the home is not listed in the Milwaukee MLS system. Is it for sale by owner?
If it is by owner, then you can either approach the seller for a showing or you can contact a local Realtor to handle the showing and the purchase should one occur.
If it has just been listed for sale by a Realtor you could contact the listing agent. But beware here, as that agent is working to make the seller as much money as possible and is solely representing their interests. The better idea is to contact a local Realtor to represent your interests.
To find a Realtor - as Don said, there are many threads on this site to help you. You could also consult friends and family for a referral. Then again, there is always the ones answering your question!! :)
If you would like more information, please fell free to contact me. I am here to help.
If it's not currently for sale, you'd probably be better off using a Realtor (though many investors buy properties without an agent). Even if a house isn't listed for sale, there's nothing wrong with making an offer.
There are plenty of threads here on Trulia about how to interview and select a Realtor.
Hope that helps.