Give a brief description of your design. Highlight any non-trivial design decisions that you took. Use slides if you want, but it's perfectly fine if you don't. Pick the salient features of your submission that you want to demo (from the list of "selling points" in your report), and demo them. A portion of your grade will depend on how well the demo goes (i.e., the fewer the glitches, the better), while another portion depends on how significant and representative your demo is.