A couple of commonly recommended beginner resources are Digital Photography School for introductory wedding tips and B&H Insights articles such as wedding portrait/drama guides.

That said, the strongest advice in the replies is: if you are completely new to wedding photography, don’t make a friend’s wedding your first solo attempt. Weddings are high-pressure, unrepeatable events, and mistakes can seriously disappoint the couple.

A better path is to hire or assist a professional, observe how they work, and shoot alongside them with permission. Pay attention to timing, posing, lighting, and when not to interfere. After seeing a few weddings handled by an experienced photographer, online tutorials will make much more sense and be far more useful.

So: use beginner articles as a starting point, but get real-world experience with a pro before taking full responsibility for a wedding.