Here's a short tutorial about how to texture models in Blender. (I apologize for the bad picture quality - they were originally intended to be 800 x 400 but the tutorial page doesn't support pictures that big):
1. Click and hold the little triangle in the top right corner
2. Drag it to about halfway across the screen
3. Hover your mouse over the window to the right and press "T" to get
rid of the Toolbar and resize the two screen until it's about in the
4. Click the small white box in the lower left corner of the right screen and select "UV/Image Editor"
5. The screen should now look like this:
6. Go into Edit Mode by pressing Tab or clicking click the Mode
Changing drop-down menu. Make sure "Face Mode" is selected on the left
hand window and select the face(s) you want to texture. Now go to the
Texture Menu on the far right hand side toolbar and click the first
option (By default, it will be a plain Texture named "Tex"). Now select
"Type" and change it to "Image or Movie" and make sure it's set as
"Texture" and not "Material." Click the "Open" Button below the preview,
7. Navigate to the folder containing your texture, select the texture
you want to use, and click "Open Image" or simply double click the
8. Make sure the face you want to edit is still selected in Face
Mode, then click the small image icon to the left of "New" on the right
window, then select the texture you want to use. Now select the small
white ball on the left window and change it to the red and white
checkered ball. This will put your view mode to Texture Mode. You may
want to Shift + D the Lamp in Object Mode a few times and position them
on each side of your model, since Lighting is enabled in Texture Mode
and will shade half of your model black.
9. Hover your mouse over the right window and press "E" to Quick
Unwrap your face. Note that this isn't a smart idea with more than 4
faces at a time. When dealing with more faces, or when modeling all the
faces with the same model simultaneously, I would recommend using Smart
Unwrap Project under Mesh > UV Unwrap > Smart Unwrap Project or
simply pressing U and selecting Smart Unwrap Project.
10. Scale your texture by pressing A while your cursor is over the
right side window until all the edges are selected (they will be bright
orange) and pressing S, then using your mouse to scale it up or down
(Scaling it up will make your texture appear smaller, while scaling it
down makes it appear bigger).
11. When you're finished texturing all the faces you want to texture,
simply click and hold the triangle again and drag it right until the
right window is darkened and a big arrow is pointing right
12. Congrats, you now textured the face of your cube.