This is how to texture in Blender. This is my first tutorial, I hope it helps. This is for 2.49, because I don't know how to do it in 2.5 yet.
You will need this texture for the tutorial (Source: http://www.filterforge.com/filters/750.jpg)
To start, make a cube. Then set the view to Textured. Then go over to the border between the 3d view and the buttons window and right click. Select split area and make your screen look kind of like mine. Turn the second window to UV
Make sure the cube is selected. Then, go into edit mode(tab) and select everything with A.
Press u-->Unwrap. A pink box should appear in the UV Image Editor screen, and the cube will turn white.
Go to Image and select open. Then choose the picture you want to use (Picture from the beginning of tutorial). Ta-da, you now have a textured crate!
One problem, when you render it, the texture is gone.
To fix this, make sure that your cube is still selected and to the Edit tab(F9). Go to UV Texture and name it Crate_UV.
Then go to the shading tab(F5) and press Add New.
Go to the Texture sub tab(F6). Press Add New. On texture type, select image.
Press the browse button next to the load button. A thumbnail of the crate .jpg. Select it. Now go back to the Material sub tab. It should look different.
It will show up when we render now, but it looks warped.
Remember the UV Texture (Crate_UV) we made? We will be using it now. In the TE window, type Crate_UV.
Go to the Map Input sub sub window. Select UV and then (then) type in Crate_UV. Notice the preview changed.
Now the crate looks real. It seems like a lot to do, but it isn't that hard. I can do it in less than 30 seconds.
If the texture doesn't look right, you can use all of the tools in this sub window to alter your texture.
Here's the finished .blend




