passing values in url to embedded form

passing values in url to embedded form

I have a form embedded in my website.

I want a contact to click a link in an email that takes them to the form and populates the form.

I can get the following to work:

tempContact  =  Contact  [ID == 1234];
input.Name = tempContact.First_name + " " + tempContact.Last_name;

But, how do I do it if I want to pass the contact ID in the url?