HTML and Php form using MySQL results in 405 error [duplicate]

I am a begineer at coding and asking my first question here.
I tried to create a HTML signup form using Php and MySQL workbench.


According to an online tutorial,
my output on submitting the form must be "Signed up successfully."


However, it is showing:


This page isn’t working.


If the problem continues, contact the site owner.


HTTP ERROR 405


This is my HTML code:



Document




Details



User Type:

Choose a user type
Admin
Teacher
Student





First Name:





Last Name:





Gender:


Female

Male

Other




Phone number:





Email:





Password:










This is my Php code:




Should i use Xampp instead of MySQL workbench or is there a problem with this code?