Ok, go to your blog, click on wallet.
steemitwallet.com will open.
Login with your posting key.
Claim rewards.

Hover over your steem balance for the dropdown menu.
Click power up.
Power up with your active key.

Do not remember your active key in any browsers.
Your posting key can be saved, but know that is less secure than not remembering it.

If you like, steemworld.org will do it, too.
But they get your steem-engine tokens, too.
Steemit does not.
Steempeak does these functions, too.

Got to steemworld.org/username.
Click on balances.
Click on claim rewards.
Enter your posting key.

Click on powerup.
Enter your active key.

Enjoy many more transactions!

If you got questions, ask.