West Virginia has what's called a "closed" primary, which means that if you register in one party, you cannot vote for candidates in another party.
At the Primary Election, if you have a party choice listed on your voter registration, you will only be given the ballot of that party. If you register with no party affiliation, you will be given a non-partisan ballot in the Primary Election. The Republican, Mountain and Democratic Parties allow any voter who is not registered with an official party to vote in their Primary Election.
For the General Election, every registered voter receives the same ballot, regardless of party affiliation. You can choose from any candidate for each office on the ballot. Hope this helps! For more information, check out the West Virginia website at http://www.sos.wv.gov/elections/Pages/Political_Parties_in_West_Virginia.aspx#5