If you have used URL (Universal Resource Locator which is the address of a web page) in generating a tag for your form, customers will have to use an http:// before their website since it is needed for a URL. But if you don't want your customers having trouble in filling out their website you can change the code from URL to Text field.
To make the changes simply go to contacts from your dashboard. Choose the form you wanted to edit.
On the right you click Generate Tag and choose Text field. Copy the code and replace the code below website on the left part of the form.
You will also have to change the code that is in your message body. Don't forget to save your changes.