I want to combine the CM sign up for my newsletter form with a form I have. In the form I have the fields Name and Surname have allready been created, so I would luv the option of adding a tickbox to my current form, which reads:
[ ] Sign me up for the newsletter.
Is there a way to integrate the two forms manually ?
Yes you can do what you want, though not by merging the forms.
You need a script running on your webserver to process the form.
This script will contain a section that, for instance, send you the contact email and another section that sends the appropriate info from the form to your mailing list using the Campaign Monitor API. This second part happens "behind the scenes" between your server and the Campaign Monitor API - your visitor has no involvement.
Exactly how you do this depends on the scripting languages you have available on your server. There are some easy to implement API kits available at http://www.campaignmonitor.com/api/