I've used Photoshop for over a decade. It's second nature to me after years of trying things out.



If you're talking about adding charset graphics, they only go in the "charset" folder.

If you're talking about changing an rpgSprite's image within the editor, click the sprite, and then click the button in its options with the person's face on it. [color=#6a7283](right underneath the button with a picture of a piece of paper)[/color]
This example video might help:
http://humbird0.net63.net/misc/rpgMaker/preview2/video.swf

If you're talking about programming a completely new sprite for the game, you create a folder inside the "sprites" folder, and follow the steps in this video tutorial:
http://humbird0.net63.net/tutorials/shooter_tutorial/5-3_changeBackground_editor/video.htm



You're most likely just trying to figure out how the change an existing sprites's image. [color=#6a7283](middle paragraph of this message)[/color]
When you place a sprite for the first time, the editor assumes that you'll want to change its charset right away, and defaults to the charset selector.
Afterwords, if you select an existing sprite, the editor will assume you likely want to edit its script, so it defaults to the script editor.
To select another charset for the sprite, click the button in the sprite's options that has a person's face on it.