How can I obtain tourist visa to china and can I use it to visit Hongkong also? I am a Nigerian.

My husband and I will like to visit China on business trip as our company has been doing business with some Chinese firms over the years. However we were told by one of our suppliers that they are permitted to invite only one person and since my husband has gone to China many times, they can only process his documents. They advised that I should apply for tourist type instead. Please advise me on how to go about it.