A good way to learn new skills in robot building and related subject is to use a tutorial, following it (or skipping it) until you have what you need to continue a project then modding away and making up your own.
One great place to start building robots is with my book, Learn Robotics Programming 2nd Edition, which tutors a builder up through building the robot, and running a first program on it. It takes you much further, by putting a camera and sensors on the robot, getting it to perform autonomous tasks like line following, object and face tracking, driving with a smartphone and speech recognition. It is a simple way to get to the point of a moving robot, and is entirely designed to be modified.
There are many educational robotic and electronic projects to get ideas. Instructables is a superb resource of tutorials and ideas to build things.
Building an AND Gate demonstration - This page has the definitions of the and gate, as well as going further and showing you how to build a basic one.
multitasking in robots - A quick demo of how do build a program that can do than more than one thing at a time.