Can you give us more information about the types of scenarios that are not working for you? I hesitate to give any recommendations, because it seems like you're mixing together a bunch of possible issues, and that could easily lead to misunderstandings on someone's part.
The first question you ask is how to get other people to speak with you. But then right after that you say that you don't know how to respond. Which I think means they are speaking to you. So what's happening here? Is it a situation where you can do back and forth for only two sentences, or perhaps four sentences? Details matter.
And then you say that you're not a chatterbox, which implies that you wish you were a chatterbox, which is totally different from the opening two questions which seem to be about getting a conversation started and not about keeping it going for minutes or hours on end.
So I guess what I'm wondering is, what scenario do you want to address first? What specific situation are you in where you're very troubled because you don't know what to say?