Open CapCut on PC
Create a New project
Import your base video and place it on the timeline
Import the overlay video or image
Drag the overlay media onto the timeline above the base layer
Select the overlay clip on the timeline
Go to the left toolbar and use Overlay (or the layer/track controls) if prompted
Adjust overlay timing by dragging the overlay clip start/end on the timeline
Resize and reposition the overlay by selecting it on the preview and using the handles
Use the crop/transform options (if available) to fit the overlay
Set blending/opacity (if available) via the overlay settings panel
Add a keyframe for the overlay (if you want movement) using the keyframe button on the transform controls
Apply effects to the overlay (optional) from the Effects panel
Export the finished video using Export/Share settings