Dear Sir or madam we are three friends with different nationality to visit china as tourist

Yes, all of you need tourist visa for China. The first step is to prepare the relevant documents: passport and its photocopy, the application form, a recently-taken passport-style photo, residence permit in UAE, round trip air tickets and hotel reservation, as well as other documents required by the consular officers.
Next step is to submit the applications to the embassy of China.

thank you for your kind reply, the other question is with this visa we can travel to hong kong also.

regards

No, it cannot be used to travel to HK. Actually, Indian and Turkey passport holders can enjoy free entry to HK for a stay of not exceeding 14 days and 90 days respectively. But Iran passport holder needs to apply for a visa for HK.