How to Cut a video together from scratch in iMovie
Create a project
In iMovie, select the Projects tab, then Create New > Movie. You’ll see your Photos library in the left pane, from which you can drag videos and images to the timeline below. Press Cmd+I to import files from elsewhere.
Add some clips
Select Photos Library, then drag a clip from the My Media pane down to the timeline. If you know the order you want clips to run in, Cmd-click those clips to select them, and then drag them all to the timeline together.
Trim a clip
Skim the pointer along the clip you’ve placed until you find where you want to begin. Click to place a marker, then drag the left-hand edge of the clip to trim its start. The edge will snap to the marker when you reach it.
Add another clip
Drag another clip into the timeline and place it after the first one. Press \ (backslash) and your movie will play in full from the beginning — note how the second clip plays immediately after the first one.
Add a transition
The jump from one clip to another can be jarring. Click Transitions above the top-left pane, and drag Cross Dissolve between your two clips. Move the playhead just before that point, and press the Spacebar to see the result.
Top of the crops
If you find a clip is poorly framed, you can adjust it. Select it in the timeline, click the Crop icon above the top-right pane, then click Crop to Fill. Drag the frame’s corners inward to zoom in or out, or drag within to recompose.
Add a title
Click Titles above the top-left pane, and select a title style you like. Drag it to the start of your timeline and type a title in the top-right pane. Adjust how long it’s shown by dragging its clip’s right-hand edge in either direction.
Adjust the transition
Sometimes you’ll want transitions to take longer, or to be snappier. Double-click the inward-pointing triangles that represent your transition, then enter a new duration in seconds. Here, we’ve sped things up a bit.
This clip is a little underexposed. To fix it, click the Color Correction tool above the top-right pane, then, just below that, drag the rightmost handle on the left-hand slider to the right to brighten your clip’s highlights.
Choose File > Share to upload your film to services such as YouTube. To save it locally, choose File from the menu. For best results, export the movie at the resolution at which you shot it. Select a destination on your Mac.