If you are more interested in making the game than designing the artwork, you may use other people's game art as long as it is copyright free. Luckily, the sites below have exactly that! Click on the logos below to visit each site. You can import any sprite into Microstudio up to 256x256 pixels in size (larger sizes may work but don't count on it!).
If you are up for a challenge, and have the time, you can make your own game assets. Microstudio has a wonderful inbuilt pixel art editor, which you should be able to learn through experimentation. You can also import game art from one of the sites above and modify it to suit your needs.
If you spend the time and effort to make your own artwork, please make it clear on your assignment webpage you have done this so I can give you the credit you deserve!
Microstudio will soon have a dedicated sound section like the 'sprites' section. In the mean time, you can create the sound in code if you are up for a challenge.
You can make retro style sounds directly by generating sound waves in the computer at different frequencies. It's a bit tricky to get started, but once you get the hang of it, it is a lot of fun. My suggestion is to check out this project, and mess around with the code in the 'music' and 'audio' files. You can also look in the documentation. Be patient and ask for help if needed.
Again, if you put in the effort to make your own sounds and/or music, make sure you write your name in the credits of your game.