Thats opening a tag.

Code: And thats closing a tag.

All you're php work goes inside those tags.
Now, if you want to print something onto the page you use this.
Code: That would output the words Hello world.

Next we are going to create a variable.
Variable's hold data.
For example:
Code:

As for checking we would use an if statement.
Code:
what this does is it checks if the data in variable $one is the same as the data in variable $two.
If it was it would have output one is equal to two but because it isnt, the else statement returned one is not equal to two instead.