I am having trouble building graph In excel with race times.

[Et2323]

I am doing a research project for school comparing running times, heart rate and O2 percentage. So my first issue is that every time I enter the times into excel they will appear as times of day later when I click on them. Yes, I have done the custom cell formating and none have fixed it. This leads to the graph not working. Second, how do I stack all three metrics on one graph and chart. Thanks.