An English conversation

I work in a shop. Today has come a tourist came by to buy something. He talked spoke in English and he has asked me if I could speak English. I answered him that I could speak a little bit of English a little. I have understood almost everything he said to me. But I have had trouble to talk to speaking with him in English. I could not say what I wanted to say. I need to improve my level of spoken English so I have to practice it more.