> I don't need to start at lesson 1; i want to skip around to different lessons.

There's a good reason for this, which I will explain with an analogy:

Lesson 1: Write the Great American Novel.

Lesson 2: Learn how to write engaging, readable short stories.

Lesson 3: Learn how to write internally consistent essays.

Lesson 4: Learn how to write coherent paragraphs.

Lesson 5: Learn how to structure grammatically correct sentences.

Lesson 6 Learn how to use and spell common English words.

Lesson 7: Learn how to enter text on a keyboard.

Get it? Lessons have a natural order, and each lesson requires what was learned beforehand.