First off make sure you navigate to the wallet, then you can go to your steem dollars part.
In that section there is a drop down where you can click sell.
Now it will open up a new tab where you can select the pair you wish to trade. We need to select Steem dollars to Steem.
At this stage you can select the amount of steem dollars that you want to convert to Steem power, then click the "manual transfer button" and copy the "account name" and "memo"
Now go back to the drop down on your Steem wallet page and select "Transfer"
At this stage the screen will pop up where you can fill in your "account name" and "memo" that was previously copied.
Click the submit button and then confirm your username and password and sign in to autherise the transaction.
Finally refresh the page to see your steem power has gone up.
And there you have it.
Hope this has helped at least one person who wasn't sure how to claim their steem power.
Remember the benefits for Steem power are that when you vote then your up vote will be more powerful and this also means you receive more rewards from that vote if your voting on good content.
Also note that Steem power can be redeemed for steem dollars or withdrawn for fiat currency so its a great investment.
Happy Steeming guys :)!