The Sketch is just the sample one provided by with the IDE.
Last time I looked, there was more than one sample provided with the IDE.
I do want the Arduino to contact my website so it can be updated from it, like Twitter is used.
Then, you want to start with an Arduino-as-client sample, and change which server it connects to.
If I call functions (text files) how?
Calling functions and reading text files are completely unrelated activities, except that reading from an SD card requires calling some functions in the SD library. Have you looked at any of those examples.
Is RSS now xml? and isn't twitter RSS?
Does it matter? What matters is what YOUR server sends out. What is your server sending in response to a GET request?
If PHP is server side that would work for an online Web-server to do some post processing right? Why rely strictly on the Arduino?
PHP is server side code. You are the one that wants to have the Arduino-as-client do something. Supposedly, that something is something that no other hardware can perform.
Can you help me with this or no?
When it is clear what you need help with, yes.