You use present perfect to say that something has happened in at an unspecified time before now. I have seen the movie twice. I have visited China several times before. Note that you CANNOT use specific periods of time. You use present perfect continuous says that something started in the past and continues up to the present. You can use specific periods of time for this tense. I have been attending college for two years. We have been driving for two hours. It's time for a break. I have been learning Chinese for three years. Note that times are not absolutely necessary. What have you been doing? I've been studying.

Continuous.