How to add borders when editing videos in adobe premiere pro?

1, PR import video material, and drag the material to the timeline.

2. Click New in the toolbar, and then click Color Mask.

3. Drag the Color Mask to the timeline, align the video material, select the color mask layer, and use the Rectangular Marquee Tool in the opacity effect.

4. Create a mask and adjust the mask to the range you want to cover.

5. Select the "Reverse" option to complete the border.

At this point, you can see the effect of the border. If you are not satisfied with the border, you can adjust the scale and move the border position.