Change colors / fonts

I like this theme so far, but I can’t figure out how I:
– change the settings of the colours of the letters (i.e. when it’s a link to another page)
– make in the menu the subs (hoovers?) another colour
– change the font sizes of The Events Calendar
– change the colors of the letters in the footers

??

Is there any help available?

Warm greetings,
Ellen