Adding Classes in source Code

Hi there,

i want to add manualy classes to an images.

To do that i change to the 'Source Code'-View an add class="example" to my image: <img src="img/path.jpg" class="example"> 

But, if i change back to the normal view in the editor, the editor delete the class ;/ so i just have <img src="img/path.jpg"> without my class

Andy Ideas how to realize adding classes by my own in the 'source code'-View?