Primary sources are documents, images or artifacts that provide firsthand testimony or direct evidence concerning an historical topic under research investigation.
A secondary source is a document or commentary that quotes or references a primary source, without first-hand knowledge of the activity or event.
A secondary source is a source other than the main source that is used to gather information. Just find another source where the same or additional information can be found.
If you are able to vote for candidates from either party then you are voting in a general election. During the primaries you can only vote for one party.