As of 2016-06-12, MyEtherWallet currently only supports voting and sending DAO tokens. You cannot execute at this time.
Find the proposal you want to vote on.
- Click on it to see the details.
Click the "Vote on a Proposal" button if you wish to vote on this proposal.
A pop up will appear.
Unlock your wallet using your private key or keystore/JSON file.
- Select VOTE NO or VOTE YES. As soon as you hit this button, your vote will be submitted, so click carefully.
- Alternatively, you can use The DAO tab by entering a specific Proposal ID.