How do I configure the Start Menu?

Either right-click the Start button and click "Properties" or right-click opened Start Menu itself and choose the "Properties" context menu item.

How do I uninstall StartIsBack?

As expected: go to Control Panel - Programs and Features, find StartIsBack, and click Uninstall.

What is activation and why is it needed?

Activation is a process of validating your license online. It ties your computer to your license via online service. It is required in order to make sure license use is not abused. One license key allows you to activate a limited number of computers.

What if I change the hardware configuration of my PC or replace it?

If you change both the hard disk and motherboard, you will need to activate your license again as the modified PC will count as new. You can activate your license on a new PC after 30 days since you used the license on the old PC, so you may need to wait until the trial period is over.