From Hubpages homepage:
Click on your account name in the top right corner.
A drop down list will appear.
Click on the first option, "My account".
Scroll down to see your hubs, listed with statistics to the right and an edit option to the left.
Click on the option, to the left of each listed hub, that says edit.
Now make any changes you like to your hub, and don't forget to save your changes at the top of the page!