If you don't see in your browser, It's possible Ponder has been disabled in your Chrome browser. Visit the Extensions Page by clicking on the to the right of your address bar and selecting Tools » Extensions and check to make sure "Enabled" is checked.
If you don't see Ponder listed on the Extensions page, then you can re-install by visiting Ponder and logging in.
After logging in, a dark install screen will drop down:
Click Install and then follow the browser prompts to approve the installation.
If Ponder is missing in Firefox, try these Firefox-specific directions.