If it's just a form, you could potentially just create a web page and have people access the page from the BlackBerry's browser, without installing an app on the BlackBerry smartphone.
If it really needs to be a whole application (and the data transfer is just one of the features), then it's a bit complicated to explain in a single comment (though I guess from your other
thread that you're already making progress). The BlackBerry JDK comes with sample code for making http connections. Also, I talked about making HTTP connections in
Chapter 9 of my book (including sample code).