Create a web page using HTML and PHP that includes the following features:
- First name
- Last name
- Email address
- Password
- Confirm password
- All fields are required and must not be empty
- The email address must be in a valid format
- The password and confirm password fields must match
- using PHP and a confirmation message should be displayed on the web page.
- Email address
- Password
- Both fields are required and must not be empty
- Upon successful validation of the login form, the user should be redirected to a welcome page that displays their first name.
- If the user enters invalid login credentials, an error message should be displayed on the login form.