Open this link in a browser:
https://v2.steemconnect.com/sign/delegateVestingShares?delegator=omwith&delegatee=raise-me-up&vesting_shares=1000000.000000%20VESTS

Then add your username, password and click submit.
You can always get your steeem power back as you open the same link and change vesting_shares to 0.

This an example for sharing about 480 SP, you can changed that number as changing vesting_shares numbers. You can asked me any questions on [email protected].