Because I am pretty new to blender I watched the tutorial Introduction to Texturing with Cycles in Blender from BlenderCookie.com.
I loaded this texture onto a sphere but then in all views the texture is just some kind of blurry with no details.
The problem is that your texture does not have any mapping defined.
To UV unwrap a UV sphere, all you need to do is:
For more info on UV unwrapping, see this post.
There are also ways to map images without UV unwrapping, such as Blended Box Mapping:
The Mapping node is used to scale up the texture.