Posting to a web page

[Len Morgan]

  I'm trying to create a "value added" front end to a web site.  What I 
need to do first is login to my account.  I suspect the the entire site 
is created in the same "style" so once I get past logging in, I should 
be able to scrape the rest of the data I need to present in LiveCode 
locally.

The login page is a simple html form with 4 "fields":

auth_vars[username]
auth_vars[password]
auth_vars[submit] Value="Login"
auth_vars[action]  Value="login"

The form will be submitted to /login.php using POST

My question is how can I create this login sequence and send it to 
login.php followed by the variables?  I know with the GET method you 
have varname=value separated by commas.  LiveCode will let me do 
something like:

post myDataString to URL "http://mywebsite.com/login.php"

but I don't know how to format myDataString in order to have it accepted.

Any help or pointers to web sites that might enlighten me are appreciated.

len morgan