Where do I create a form and find shortcode

It very much depends on the plugin. Some plugins add a new tab to your toolbar. However, some other plugins add a new button to your text editor. Anyhow, after creating your form and receiving the shortcode, all you need to do is to copy and paste it into your text in the editor and it should appear on your website.

Jetpack has an easy to use form builder as well, if you’re looking for something more light weight. It’s documented as a contact form but it can be edited to represent pretty much anything you want.