If you need to vote by manually interacting with the voting smart contract you will need to call the submitVote function with 2 parameters:
Submit to the smart contract, which can be viewed here. Attempting to submit more than one vote per address will result in an error, and the transaction containing the duplicate vote will be rejected.
The smart contract uses a merkle tree to verify that a voter is eligible. The root of the tree is already in the smart contract. The proof is an array of values which the contract combines with the address submitting the transaction (i.e. your address) to verify your eligibility.
The tool below will generate the proof for any address. The proof must match the address that is submitting the transaction..