How do I get html5 on my iPad?

You don't need to download html5. It is not a plug in.

From Wikipedia....

HTML5 is a language for structuring and presenting content for the World Wide Web,

If the web site that you want to view is using html5, then then content will be viewable for you. You cannot convert Flash content to html5 on the iPad if that is what you want to do. html5 content has to be "built into" the website for you to view the content.

What exactly are you trying to do?

Sounds like you are trying to download a file. This cannot be done by default on any iOS device but can be done by using any number of the"free music download" apps. These allow you to save the file in the devices memory for download and access through iTunes but will still not allow a direct install to your device. You cannot install directly onto the iPad from a web page.

The above info on html5 is correct. It is not something you can download like a flash plugin but is the language that is used during the design of the web age.

There is no downloadable "HTML".

http://en.wikipedia.org/wiki/HTML

And, safari reads html5 files.