Photoshop Introduction

Crop Tool- A tool to resize your image & make it smaller.
Lasso Tool- A tool to select a specific part of the photo & make a shape into it.
Text Tool- A tool to insert text on your photo.
To undo a mistake you made you just press "Command-Z" or "CTRL-Z".
To undo more than on action just pull up the "History Palette. You can do this by clicking Window--> History Menu.
To rotate an image just go to the image menu & select image resolution.
If you don't like your initial cropping box you drew, you can press --> ESC to cancel the crop.
When you enter dimensions as you crop, you're telling photoshop which dimensions the image should result in after you crop, The crop box will be forced into a certain ratio.
Newspapers & Newsletters are likely to have resolutions in the range 150 to 200 ppi, & magazines are likely to have high resolution of 250 ppi or more.