You can export your form using the methods described here: http://app.formassembly.com/pages/support/publishing
into an external site. If you have a web host currently or run your own webserver on that domain, all you need to do is integrate your form into an existing page or create a new html page to place the form into.
You can use the "Publish on your own website" option in the "Publish" tab to export your form's HTML for use at your own domain. For more information on hosting your form somewhere besides www.tfaforms.com/, check out http://app.formassembly.com/pages/support/publishing.