Clicking the arrows is correct, however the reason your votes are not working is because you don't have enough points.
40 points to vote up and flag
100 points to vote down
See a full list here
You only have 20, which is the amount all users start off with. To be able to vote, you'll have to answer questions/ask questions and hope that other users upvote your answers or questions, or your answers get BAed.
To check how many points you have, just go to your profile. Here's your one;