How Do I Edit Patterns In The Composer on page 61 describes how to increase the measures in the composer, and how to edit a part to produce an 8 measure pattern with 8 recognisable measures before the pattern repeats, from a smaller pattern.

How Do I Edit Composers With The Sequencer on page 65 describes all the principles of sequencer to composer copy and is exactly applicable to midi files if you follow the steps above.

The following chapters on Performance Pad creation and editing are also just as applicable to the composer.

If you follow all the practical examples from beginning to end of the book in order you will have a grounding in all the principles of editing which can then be applied to many different circumstances and applications.