How can I read the Rakuten stock graphs?

I’m looking at my investments on the Rakuten site (for example, ｅＭＡＸＩＳ Ｓｌｉｍ 米国株式（Ｓ＆Ｐ５００）).
At the top it will have the base price in black, And in the same cell will have an either green or red value, both a yen amount and percentage. What exactly do these values mean?

Also, further down the screen there’s an actual graph which has two modes, “base price” and “performance”. How are these different?
More importantly, The actual graph is done in three different colors. What exactly is the difference between these colors?

Out of all this information, which information is most important to know how my stock is doing, and if it’s a good time to buy or not?

Thank you!