A build is the way the picture or words come in. If you go to the inspector at the top the third box is the build section. Here you can select any type of effect you want and if there is the direction option you can change that too.
A transition is the way the slide switches to the next. It is the second slide in the inspector. You can change the slide transition to automatic and the the way it changes, for example if you wanted sparkles or the shimmer effects.
To change your slides to automatic go to transitions in the inspector and instead of the on click choice change it to automatic.
To change the color of the letters in your keynote next to the inspector, click on colors here you can mess with the color wheel. But you have to have the word highlighted