Hi Jenny,
Have you made any progress while waiting?
The link you posted looks like an experiment conducted in a university lab, one equipped with a spectrometer. Do you have access to one and someone who can show you how to use it? At first glance this looks to be a very equipment-necessary experiment for a high school project.
Also, I do not think you will be able to purchase and properly store myoglobin. You may still find the experiment rewarding but much more achievable by measuring the changes in protein urea solutions using an easier method. One common method is to observe changes in an egg. Maybe you could do something like modify this experiment:
https://www.education.com/science-fair/ ... -proteins/ but using urea solutions.
9M means 9 moles per Liter, which is simply how many molecules of urea are in 1 liter of solution. (1 mole=602,200,000,000,000,000,000,000 or 6.022x10^23 for short). If you have adult help, I think you can purchase solid urea to dissolve yourself. However, probably what you will end up needing to do is purchase some urea, which will not be as concentrated as in this experiment because it is a dangerous chemical so only labs with safety equipment should buy it at full strength. Then, you can experiment on the egg with different amounts of that purchased solution, diluted into buffer solution. You cannot just use water.
A buffer solution simply makes sure the urea does not turn your solution too acidic or basic. You may be able to purchase a buffer solution powder to mix with water. You could maybe use artificial seawater? or a common lab one is phosphate-buffered saline.
Sorry this isn't exactly what you originally thought of. I would definitely check with your biology teachers to see if they have the resources necessary to do this and are willing to help you at school, otherwise the experiment you linked to will be impossible at home.
Good luck!