Discover the Eraser Tool

Choose the Eraser tool from the toolbar. You'll notice a letter next to it. This is the keyboard shortcut (E) which selects the tool.

Duplicate the background layer of a photo by dragging it to the new layer icon on the bottom of the layers palette as shown.

Since this image is just for training purposes I'm going to fill the background layer with white. As long as I Save As: with a slightly different name (which saves a Copy) then the original image will always be retained.

Normally I would keep a copy of the original untouched layer on the bottom of the layers palette but in this case I'm just showing you how to use the eraser tool.

Now that you're on the eraser tool, just drag it around the image for areas that you want to 'erase'. Note that you are using a 'brush'. You can also choose Pencil or Block for erasing. I always use the brush. You can change the brushes size and aspects (shown later).

Note how the pixels are being erased on this layer of the flowers. They are only being erased on this layer because it is the one layer selected in the layers palette. Whatever layers are beneath will show through (as you can see the white 'background' layer). When I turn the background layer eyeball off you can see the Photoshop gridspace.

Pretty crappy choice of an image for erasing but I'm not trying to get a selection here. Just get comfortable using the eraser tool. In all reality I'll use it to clean up selections (covered in Basic Photoshop DVD's) but not for much else because there are other more powerful tools that await you. Nevertheless you must have an understanding of these basics so you can move on and have general proficiency for image editing or graphic design.

Here you can change the diameter and hardness of the brush. You can use this drop down menu in the options bar (Photoshop 7 & above). Oftentimes you may need to use a smaller eraser brush for erasing.

The keyboard shortcuts are [ & ] for getting a smaller or larger brush size on the fly.

I'm just showing that the Block eraser does the same thing but might work for you in 'tight corners'.

You can also lower the brushes opacity. Many tools allow you to lower the opacity of the tool itself without affecting the layers opacity. Lowering the eraser's opacity will leave some pixels visible as 'grey' which is in between in luminance.

The history palette you'll be hearing a lot more of. Just go back in time to the step where you want undone. When you do an action after going back, be careful because the history will pick things up from there again.

Basic Photoshop DVD Training goes into the Brush palette, loading brushes, defining brushes and working with the brush options. You can use the Brushes palette to choose an eraser brush when you are on the eraser tool.

Here is a sampler of a 'star' eraser (brush).
It is erasing pixels in the shape of a star...normally you'll want to stick with the rounded brush (take it from me).