If you're just starting out in video work, getting a good grip on editing b-roll can do a ton to make your output more interesting and create a stronger narrative. Here's how to cut and edit it in along with your main footage.
B-roll is important stuff. Though supportive in nature, it adds visual interest to your work that keeps the viewer more engaged and serves as an informational bridge to aid in your narrative. While capturing it is its own art unto itself, editing it in alongside your main footage takes a certain finesse, and this great tutorial from Justin Odisho will walk you through all those steps and options, of which you essentially have two: playing the clip audio over the b-roll so that the aural narrative is uninterrupted or placing it after the main footage and augmenting it with some sort of supplementary sound. While both are perfectly valid options, each lends the final product a different feel and narrative flow, creating emphasis in different manners. Be sure to watch the two examples carefully to see how they render differently and to get a feel for which is appropriate for different situations.
[via No Film School]