Hello, Photoshop CS or Elements & Lightroom are pretty much industry standard software for working with photos these days. If you are a digital photo pro or graphics person, you pretty much have to know PS or an equivelent (which in my opinion, there are none, but that is only because I know PS best).
There are classes offered at any self respecting art or vocational school and most community collages, but they can be pricey and time consuming. There is a lot you can learn from library books and online resources for free. I just added a resource on this blog offering some tips on PS that you might find helpful. Please check it out in the side bar.