Control flow and decision-making lets programs make decisions in ways that you pre-determine. Loops let your program perform a single operation multiple times (which makes your programs much more efficient). Between if-statements and loops, you can now accomplish almost every single task you'll need to accomplish (though you'll learn techniques later that make your life even easier).
Before you begin these problems, go through these exercises and materials:
Control Flow and Decision Making
- Sections 7.1 and 7.2 of Chris Pine's book - codecademy's Control Flow in Ruby course and associated exercises - Exercises 27-31 of Learn Ruby the Hard Way
Loops
- Sections 7.3-7.5 of Chris Pine's book - The "Looping with Ruby" track of codecademy.