When you say you are learning to build a robot, you have plenty of robotic projects, articles and DIY's all over the web. Google with the required keywords. Cheers.
you need to know about:
- DC, servo and stepper motors how they work.
- H bridge circuit and its uses with DC and stepper motor.
- speed control using PWM.
- microcntroller programming and interfacing, i recommend for you PIC microcontrollers, easy to learn, much resources available and support anywhere.
- sensing techniques like line tracking and ultrasonic, also microswitches and obstacles detection.
- sure basics like transistors and relays.
- learn about some mechanical design issues like gearing, belts, levers, i recommend for you chapter 5 "mechanical systems" from a "modern control technology" by kilian.
-DC, servo and stepper motors how they work: 1 day
- H bridge circuit and its uses with DC and stepper motor & speed control using PWM : 1 day.
- microcntroller programming and interfacing: 7 days
- sensing techniques: from 1 to 3 weeks
-----------Total: 1+1+7+ 7 or 21 =16 to 30 days max.
i think 30 for a student isn't a big deal but it depends on the documents you will start from, take care of choosing such material.