Here is a Quick Overview - hope this helps you :)

After logging in, visit the your "Dashboard", here you will see your standart steem/steempower wallet. Besides that you see a value of "Upvote Credits", these are basically Credits which you can spend to get upvotes on your posts. To earn these Credits you need to enable "Auto voting".

If auto voting is disabled, click "Turn Auto Voting on". Now you we will start upvoting posts with your account (you can specify how much posts we upvote on your behalf with the slider next to the "Turn Auto Vote On" Button - Higher percentage means less upvotes, means less credits for you).
You can keep track of all upvotes we've done for you on the statistics page. For every upvote you will receive credits, the amount depends on how "strong" your account is (means how much steempower you own).

After you earned enough credits , you can spend them on one of your posts with the form in the lower left of your dashboard. The Amount of credits represents the strength of one (or multiple) votes.

1 Upvote Credit is worth one 100% Upvote from a user with 10 Steem Power.