[xapata]

Why do you want to converse with people in German, rather than English? If you don't have a satisfactory answer to that question, you probably won't be able to speak German. "Because I think I should" is not motivating.

People learn languages best by simply listening to others talk. Hang out with folks that are speaking German. Tell them you want to hear no English at all, all night. Do this for a few weeks, maybe months, and you'll be speaking German soon.

Edit: Maybe I should add that you should focus on comprehension before speaking. Try to simply understand what other people are saying, first. While at an intermediate level, you'll find that you can understand a friend well, but a stranger almost not at all. It'll take some time listening to a variety of people before you can understand many speaking patterns.