If you are already a graphic designer, you will be able to adapt your skills
to the Web easily, although this will not excuse you from acquiring a solid
understanding of HTML, CSS, and other web technologies. Because most
sites have at least a few images, even hobbyist web designers will need to
know how to create and edit images, at minimum.
Again, I want to note that all of these responsibilities may fall into the hands
of one designer who creates both the look and the functionality of a site. But
for larger sites with bigger budgets, there is an opportunity to find your own
special niche in the design process.