Good point, there is a distinct difference between the skill sets required to be a developer vs. a designer.
However, many of us wear both hats, either by necessity or desire to be more employable.
I would advise that you start with the simple stuff -- HTML, CSS, and if you fall in love with it, then the more advanced stuff will feel like a natural extension and you will WANT to learn them.
I started "playing around" with Photoshop about 10 years ago and after many hours of PRACTICE, I can say that I'm *almost* as good as a graphic designer with this tool. I would say intermediate/advanced skills. It's a great skill to have if you want to set yourself apart.