One of the most important skills any wedding photographer needs is the ability to quickly and effectively use artificial light in both a practical and creative way, whether it's to supplement or supply the light for a scene. This great video will show you a few techniques, tips, and tricks for using off-camera flash in wedding scenarios.
Coming to you from Taylor Jackson, this great video shows how to use a speedlight as an off-camera flash in wedding photography. For these, Jackson uses the Godox V1, but the techniques and tips apply to whatever speedlight or small monolight you would like to use. When you're shooting weddings, you don't get control over the locations or the weather, and you'll often be in less-than-ideal or downright horrible lighting conditions. Add in the time pressure of a wedding, and it's quickly apparent why it's so important to be proficient in quickly creating off-camera flash setups that are efficient and produce pleasing results. Check out the video above for lots of helpful information on the topic.
Also, if you really want to dive into the world of wedding photography, check out "How To Become A Professional Commercial Wedding Photographer."