Press delete to make this part of the image transparent or tap Command+C to copy your selection, making it available in Clipboard. The more you drag the cursor the more of the image will be highlighted in red to show you have selected it. Just click the area you want to select and drag your cursor. When working with a PDF this becomes a rectangular selection tool.
It also provides Lasso and Smart Lasso selection tools, on which more below. The Selection Tool: This lets you choose to select an item using a Rectangular or an Elliptical tool.This tool is not available here when working with images. Text Selection: When working with a PDF a text selection tool sits at the far left.