How to search for date between

This is how I understand your questions, let say you have an existing table name tblVotes
and you already have data of voters with the ff. fields

VotingDate - the actual voting date which you said the system will only accept
IsVoteAccepted - boolean field indicating if the vote is accepted

//variable
VotedDate - this is when the user cast their votes

Sp might look like this

USE Votes
GO
CREATE PROCEDURE usp_Votes
    @VoteDate Date
AS 

     UPDATE tblvotes
     SET    IsVoteAccepted = 1
     WHERE  VotingDate <= @VoteDate
GO