Okay. So first design the HTML which is going to contain that drop-down. You know what HTML element you're going to use, right? (If not then that's the first thing to find out.) Write out an example with a couple of entries in it.
Once you have that, then you know what your JSP should be generating. But it needs some input to work from. So
you should have a
servlet that extracts the data required to produce the drop-down and puts it in a list of objects. Add that list to the request scope and forward to the JSP. The JSP will contain some JSTL code to produce the drop-down from that list.
That's just a general description. But hopefully you can see that there's several different parts of the design. Don't try to do them all in one lump, do them separately. It may happen that you have to redo one part of your design when you find in some other part that there's something missing, but that's normal in the design process.