The big secret to programming is that all you need to begin is curiosity. 4 years ago, I didn't know how to program either. In school, I majored in a completely different discipline. You don't need to have a CS degree, unless you plan on being a software engineer for a large software company.
To begin, think of a fun problem. You said you don't think you have a chance of creating the next Twitter, but why don't you try replicating some small portion of Twitter? What makes Twitter complicated is the scale, but you can create a very simple post-to-feed app and learn how to deploy it to a server just by using Google and StackOverflow. Creating working prototypes of even the simplest ideas gives you the courage to pick up more ambitious projects. The cool thing about code is that you can always re-use (read: even straight copy/paste is ok) what you've done before to further yourself in future projects.
To begin, think of a fun problem. You said you don't think you have a chance of creating the next Twitter, but why don't you try replicating some small portion of Twitter? What makes Twitter complicated is the scale, but you can create a very simple post-to-feed app and learn how to deploy it to a server just by using Google and StackOverflow. Creating working prototypes of even the simplest ideas gives you the courage to pick up more ambitious projects. The cool thing about code is that you can always re-use (read: even straight copy/paste is ok) what you've done before to further yourself in future projects.