eHow is not the same type of reference site as Wikipedia - it's not an encyclopedia. It's basically a collection of articles written by the public but eHow does make a reasonable effort to ensure that only articles written by knowledgeable people are accepted for publication and this keeps their content standards quite high.
eHow does offer compensation for articles they accept for publication so if you are an expert in and field and feel like sharing that knowledge and making a few bucks then writing for eHow might be a good choice.
Of great personal interest to me is the fact that they also have over 150 000 eHow videos. Instrucional video clips are often far easier to learn from than written guides - especially when it comes to things like learning songs on guitar.