These are some of the more common colours that you get from mixing primary colours:
Red and blue makes purple (add a little white to get lilac, mauve etc.)
Blue and yellow makes green.
Red, blue and a little yellow makes brown.
Red and yellow makes orange.
Beyond these basics, you need black and white as well, to get darker and lighter shades - red and white for pink, blue and a little black for navy blue etc.
There is a website on colour theory which can start you off with some more detailed ideas about colour mixing. It's at painting/ colour theory
The main thing to remember is to add a very, very little colour at a time -you can always add more, but you can't take it out once it's mixed.
Red and blue makes purple (add a little white to get lilac, mauve etc.)
Blue and yellow makes green.
Red, blue and a little yellow makes brown.
Red and yellow makes orange.
Beyond these basics, you need black and white as well, to get darker and lighter shades - red and white for pink, blue and a little black for navy blue etc.
There is a website on colour theory which can start you off with some more detailed ideas about colour mixing. It's at painting/ colour theory
The main thing to remember is to add a very, very little colour at a time -you can always add more, but you can't take it out once it's mixed.