there's not going to yet be any official candidates for that primary. I see that your primary is held on March 1, which is fairly early. My guess is that the candidates will be filing starting some time in the fall.

Here's a link to the Democratic Party of Virginia website: http://www.vademocrats.org/

You could call them tomorrow and see what they tell you. The Presidential Primary is statewide, so your county won't matter.

but all so old enough to have forgotten.

The 2016 Virginia primaries have tentatively been set for Tuesday March 1st, 2016.

http://virginia.state-election.info

Our commonwealth has an open primary system: http://law.lis.virginia.gov/vacode/24.2-530/

As far as 2015 elections, if your county has any, this might help: http://ballotpedia.org/Virginia_elections,_2015

Hope this helps!