Control + A is to apply the scale, to reset it to 1, 1, 1. Basic topics are covered in The Blender Basics Course and Fundamentals of Mesh Modeling. Linking up, it’s better to watch those courses first:
https://cgcookie.com/courses/blender-basics-an-introduction-to-blender-3d-4-5-lts
https://cgcookie.com/p/core
