Draw rectangular selection borders

On the Photoshop on the web homepage, select Upload file and browse for a file on your device.

Choose Select > Rectangular marquee .

In the tool options bar, set the Feather amount.

Drag to draw a rectangular selection border over the area you wish to select.

In the tool options bar, use Select more  or Select less to add to your current selection or subtract from it as necessary. 

Select More options and choose from the given options:

• New selection: Creates a new selection.
• Intersect with selection: Combines it with the previous selection.
• Style: Sets how the marquee tool draws.
• Refine Edge: Refines the edges to improve the initial selection.

In the Contextual task bar, you can further refine the selection with options such as Generative fill, Create mask, Adjust, Invert selection, Content-aware fill, or Deselect.