Any generally accessible world wide web site whose subject is primarily related to the field of science fiction, fantasy, or fandom, and which had content generally available during the calendar year 2001. You don't need to do anything. All web sites that meet the definition of the award are automatically eligible. No, the Hugo Awards are international in scope. This should be particularly the case for the web site award as web sites can be easily accessed regardless of where in the world they are based.
Voting is in two stages.
The first stage is a nomination process in which voters are allowed to suggest up to five entires for each category in the Hugo Awards. The top five nominees then go forward to a final ballot. Nomination is open to all members of the current and previous year's Worldcon. The final ballot is voted on only by members of the current year's Worldcon. Nominations for the Best Web Site Hugo will thus be open to members of ConJos and to members of The Millennium Philcon, the 2001 Worldcon in Philadelphia.