Start by taking some CS classes, or get some good books. Do you have a computer you can write code on? If you want to start with Java, then get the JDK (or whatever they're calling it now) installed. Start writing simple programs. "Hello, world." is really where you want to start.
Don't expect to code an application like Facebook in your first few months of coding. Pick some small project, like a calculator or a checkers program, and see if you can figure out how to approach a project like that.
Read a lot - books, other people's code, forums (like this one). Ask questions. Don't give up. Realize there will be days when you do nothing but bang your head against the wall and make ZERO progress...as well as sudden breakthroughs in the middle of the night. Don't take criticism personally. Embrace any and all advice given, and really try to understand what people are telling you.
Finally, have fun learning!!!
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors