You say you are part of a "team". What tasks have been assigned to others? That will somewhat determine where you need to apply your focus. For example, if someone else is the "artistic director" in charge of graphics (logos, photographs, "clipart", etc.) then part of your job is done. You just need to coordinate with that person. If another team member is in charge of page layout then you shouldn't have to worry about that either.
All that stated, if you want to learn webdev you really should at some point learn all these things, or at least have a working knowledge of them.