What kind of visa do we need?, what do we nee to apply? how long is the process?

Hi,
We area a family of 4, we are planning our vacations for next summer to China with a group of people for 15 days. My husband, my two kids (they are US citizens, my kids will be 11 and 8 years old at the time of our vacations) and my self (US permanent resident) need a tourist type.

Thanks in advance