Do not forget to connect your wallet, which has Fund's LP tokens in it. Only fund's members are able to vote on fund's proposals.
Go to the Fund's info page and see all active proposals there:
You can see all active proposals
Click on Proposal you want to vote on and you will see the screen below. On the left side, you can see the text name and description, which was sent by the proposal's creator, proposal's start date and the creator of the proposal. On the right, you can see Proposed Value, that's being change and its' current value. You can also see "Votes" history, where you will see all previous votes, that's being made on current proposal.
You have 3 options to vote: "For", "Against" and "Abstain". Let's vote "For" in this example. Click on "for" button and approve the transaction from your metamask.
Please note that if the proposal is created before the investor's deposit, he will not be able to vote for security reasons. Only LP tokens that are minted before the creation of the proposal are eligible for voting.
After Voting finishes, anyone is able to execute proposal. Check here how to execute the proposal: Execute proposal