At risk of insulting your intelligence, Giorginetto, here is a translation of the relevant parts:
Page one:
Menge= quantity. (insert how many you want)
In den Warenkorb= In your basket (click on this)
Next page:
Change quantity if you wish and click on Aktualisieren to confirm the change or Warenkorb leeren to empty Basket
zur Kasse gehen= Checkout
Next page:
Als Gast zur Kasse oder registrieren= Checkout as Guest or Register (choose Als Gast zur Kasse gehen) and click on Fortsetzen (next)
Next page
Rechnungsadresse (Billing Address)
Fill in Vorname (first name), Nachname (last name) E-Mail adresse, Adresse, PLZ (post code), Stadt (town), choose Land (country), Telefon (telephone number)
select or deselect Angemeldet bleiben (=stay logged in)
select An diese Adresse verschicken (send to this address) or An andere Adresse verschicken (send to another address if you have a different Delivery address.
Fill in Lieferadresse (delivery address) if you need to
Next page Versandart (Shipping) will tell you the shipping cost
Next page Zahlungsinformation (payment details) allows you to choose how you will pay
Next page Bestellübersicht check both boxes if you are trusting and dont want to translate the small print!
Next page Credit card or other payment details (card number, valid to (month), valid to (year), CVC code.
Hope that helps!