So if you have your html file myfile.html in a folder, say mydir, all you have to do is:

cd /path/to/mydir-with-index.html-in-it
python -m SimpleHTTPServer 9000

if you have node.js installed, an ever better server is:

cd /path/to/mydir-with-index.html-in-it
http-server -p 9000


Then point your browser to:

http://localhost:9000/