JSP is designed for presentation. The basic presentation is formatted using HTML. You need have a good control of HTML forms, frames, and more importantly, client-side JavaScript. You don't need to know all things, but you should be able to get references as you need them.

However, you don't need be a graphic expert.
Usually, you make things work and at a later stage, some GUI guy will lay out the pages for the whole site. Some people are proud that they know some graphic tools such as Photoshop. If they cannot be a graphic expert, such a skill does not help much. For JSP programmers, the most important thing is
functionality. I hope I have get myself acrossed.