Photoshop is basically made up of four areas: the menu bar, at the top, the toolbar just below it, the toolbox on the left and the palettes on the right. The menu bar and toolbox always stay the same, as they contain the different modes and options that you can choose, but the toolbar changes depending on context.
An updated status of your image is provided by the palettes. This includes a history of all of the actions and changes you have made along with a thumbnail image of the current results.
Let's take a look at how the interface changes depending on use. From the toolbox, select the type tool (it looks like a capital T). Notice how the toolbar changes completely to enable you to set the font name, size etc.
In the history palette, your use of the type tool will be added to your history, and a new layer will be created for your text and shown in the layers palette.
No matter the project you are working on in Photoshop, you will most likely start with either the toolbox or the menus. Everyday tools and features will be found in your toolbox, such as selecting, filling and making shapes. The menus contain the more advanced functions such as blurring, sharpening and all of the other possibilities Photoshop can provide, most of which are found under the Filter menu.
Once you have chosen a tool from the toolbox, you can adjust its settings through the toolbar. In this, options from the menu will typically open a dialog box. Should you want to go back and make a change to something you have done to your image, use your palette history for the quickest fix. Experiment with the palettes as they have other uses also such as changing colors, naturally under the colors palette.