1) How to insert an image- Click on the file menu, then select open, It will then display a dialogue box, in that click browse to search for your image, after selecting it click okay, the selected image will be added to your photo shop, continue opening many files.
Select the Eraser tool
Set the background color you want to apply if you are erasing in the background or a layer with locked transparency.
In the options bar, choose a Mode setting. Brush and Pencil set the eraser to act like those tools. Block is a hard-edged, fixed-sized square with no options for changing the opacity or flow.
For Brush and Pencil modes, choose a brush preset, and set Opacity and Flow in the options bar
An opacity of 100% erases pixels completely. A lower opacity erases pixels partially. See Paint tool options.
To erase to a saved state or snapshot of the image, click the left column of the state or snapshot in the History panel, and then select Erase To History in the options bar.
Drag through the area you want to erase.