Voting power is something that you have from your total amount of Steem power.
The more steem power you have, the more voting worth you have.
To get more steem power, you need to power up your STEEM.
This can be done by click your STEEM balance and selecting power up.
Please note to withdraw STEEM power, it'll take 3 months. Don't power up unless you don't want to withdraw that money for at least 3 months!