How do I do that exactly?
Using avast Internet security is one way to get sandboxed web browsing.
"avast! Internet Security includes all the features you need to be safe"
"Sandbox
An isolated virtual environment, so risky sites and apps cannot harm your PC."
If using avast free AV you can use Sandboxie and run your browser in it.
sandboxie DOT com
"Sandboxie runs your programs in an isolated space which prevents them from making
permanent changes to other programs and data in your computer."