I need to send a site.com link to all contact which will have event registration information through email. When user click the link it need to take them to site.com web page which will not ask for user name and password. When user input the value and hit submit all record should be saved in salesforce Event Registration object with all information. Can any one help me how to build the link so that user can register without login into salesforce.
You will need to create a visualforce (VF) page that captures the data you want to capture.
Once you have completed the VF page, make it available in your site by adding it to it.
The last step is to click on the 'Public Access Settings' in the site and allow the Guest Site User to view the page and to edit the fields you modify in your VF page.
Youu can then sent the link of the page via email.