You can bring in images directly from a TWAIN compatible scanner or digital camera.
If you have more than one TWAIN compatible device on your system use File->Import Image->Select source to select which device you want to talk to.
If you want to quickly scan in an image simply press the Scan button 
or select File->Import Image->Acquire image from the menu.
After bringing in an image from the scanner you may want to crop and resize the image.
Note: It is possible to bring in a very large image from a scanner. You may need a fast PC with a good deal of ram to effectively optimize such an image.