THE BASE OF PHOTOSHOP

We start with the basic file->new

we have your basic presets which set up your width height and resloution as per the preset

If you chose custom we get to chose our width and height in pixles cm inches anything you want 

we then have the colour modes... each mode has its own speciality and use

they are :-

Bitmap-its a one bit colour mode works with bits(pixels)

Grayscale-mostly used with black and white prints it consits of colour only between black and white like              gray (hahahaha) hence the name

RGB-it is the red green and blue channel uses light to colour used only when using for digital media like computers, projectors and TVs.

CYMK-used for print media like posters papers etc printers use these colours it stands for Cayan Yellow Magenda and Black.

LAB-(not sure) it the type of color schem used in photo studios.

thats that for the basics of starting out a new file.............

points to remeber :-whenever printing use CYMK and if you have to publish online use RGB