How to Crop
To crop in Premiere, you will need to apply the Crop effect to the clip you are editing. Here's how to do that.
In the top right corner, select the Workspaces icon, and then select Effects. This will rearrange some of the panes in your project window.
In the right column, select Effect to expand the choices under it. Then select Video Effects -> Transform -> Crop.
Drag the Crop piece onto the clip you want to crop.
Select the clip, then select the Effects tab, and then select Crop to expand that section.
You can then expand each section and use the slider to adjust the cropping.
You can then double click the preview of the clip and drag the white squares to zoom and reshape the image. You can also click and drag the image to reposition it.