It would take hours or days or years to give you a tutorial. Thankfully, there are already some tutorials out there. My fave is

Such a great program.

If u r using Photoshop CS2 follow these steps:

1. If you want to make a picture (writing on it, make some good stuff) you go to file then New and a white page will appear. if u want to write, on the left of the screen there’s a toolbar u click on the option ( letter T ) and u can move the cursor of the mouse and write wherever u want and on the top of the screen u can configure the font, size, and shape. if you want to design or the style of the text u wrote go to the 2nd box on the right of the screen where u can c history, style… click on style where a number of small squares are displayed keep switching styles until u find the best 1 u like. U can try all the tools in the toolbar on the left of the screen…

2. If you want to change qualiity and all things in pictures, you put file, open, and open the pic u want to configure. if u want to crop the pic u go to the toolbar on the left and choose the option where u see 2 squares coinciding each other. if you want to change the quality and save it you can go to file, save for web and a menu will appear then u can play with the quality and and contrast and other things and be careful to save it as a .JPG file format.

I beleive the rest is for u to discover.
hope my small tutorial helps u.
gd luck