System fixes

[login to view URL] I need the following questions in my system: 1- You need to standardize the connections to the database. In the current file it creates database connection in each file and could be done through an include with the database configuration file. 2- You need to log in to each page 3- I need to standardize the “ENTRAR” and “CADASTRAR” button. When you click on [login to view URL] and it opens a poup and when you click the button at the top as well. The information and styles are different. It must be standard. 4- In the [login to view URL] file it has a variable that pulls the user data from the database. It needs to be in all the files, because it is the login of the user. 5- In the file [login to view URL] I need that when you select a number and press on "reserve" it freezes that number and go to the database the numbers that that login selected I need it done inside my server or if I have an online development server I can also accept. the files are attached