How could I blocked a web site on my computer so no one could get in that web site?
Need information

Some general ways in no particular order or efficacy:
1. Install parental control/filtering software.
2. Block network traffic reaching site via firewall software/device.
3. Add site to Internet Explorer's Content Advisor allowed/disallowed site list.
4. Disable Internet access via Windows Group Policy.
5. Increase computer's login security so that credentials are required to use computer.
6. Unplug network cable.

Additional situation specifics may solicit more appropriate responses.