What is the best way to use an insulin pen (novorapid (insulin aspart) novolet)?

Carefull: Novolet is the first prefilled and disposable pen available meaning youvare done with it you throw it away, it implies that it filled with nph insulin. Novorapid (insulin aspart) on the other hand is a brand of fast acting Insulin that comes in cartriges that can go on the novopen which is a refillable pen(you do not toss it you change the cartrige. The first one is slow acting Insulin the second fast. Like apple.