Launch first attachment from web browser

I have a web form with a file upload control to attach a word doc (orr any other doc actually). It saves and when reopened does nothing even though the form property has launch set to first attachment

Any ideas

Subject: Launch first attachment from web browser

Dear Chris,

This property is only for notes client.You can use javascript’s onload event for opening file attachment.make a url and use in to a form’s load event.

Rishi

Subject: RE: Launch first attachment from web browser

a cunning plan, only I am crap at Javascript.

I have a field that computes the document launch URL as the document is saved so it is already available. Can you assist me in understanding how to use it in the onload event please