There's really not much to "train" on. It's a simple HTML form, with the data sent to the salesforce.com website, where it is processed asynchronously as resources allow.
I would recommend Guidelines for Setting Up Web-to-Lead, Generate Leads from Your Website for Your Sales Teams, and a simple YouTube search that has plenty of short clips you can watch about configuring and using Web-to-Lead.
Basically, in summary, all you need to do is go to Setup > Customize > Leads > Web-to-Lead, generate the HTML, style or customize it as you want, and put it on your page. You should always start by generating your own HTML, as it makes sure that the custom fields for your organization are accounted for.
The basic URL is located at:
The basic format is a POST request, with url-encoded parameters, using the application/x-www-form-urlencoded Content-Encoding header.
The required parameters are
oid (your organization's ID), and
retURL (the "thank you" page).
Other parameters will depend on what fields you want to collect; use the online form generator to make sure you have the correct field names.