As you all are very much aware of by now, your startup project should be about (i) an engineering design problem (for a product and/or service) that (ii) implements the solution of (iii) the idea you have had to solve a problem the world needs to be solved.
Five (5!!!) years of engineering education should have given you all the required tools and thinking methodologies to navigate through the design engineering process that must be at the heart of your project. Nevertheless, in case of need, here is a decent source of information (with all limitations of Wikipedia) from where you can find countless other sources of information to address your willingness to learn!!
https://en.wikipedia.org/wiki/Engineering_design_process