The most widely distributed newspaper in Wyoming is the "Casper Star-Tribune". It does not cover classifieds for the entire state.
This link will take you to info for many newpapers in Wyoming.
It should be noted that not all newpapers are listed at this link.
Searching for newspapers in Wyoming, one must realize that some towns do not have their own but are published under the name of the county.
For example, Evanston WY has no paper - but the local paper is the "Uinta County Herald".
For extra help, google-search the town and county - be sure to include the state.
ex: "Evanston Wyoming newspapers" or "Uinta County Wyoming Newspapers".
http://www.50states.com/news/wyomin.htm