I'm Iranian, work in Oman for three years, how can I get a China visit visa for me and my family?

I am holding Iranain passport, I am here in Oman almost three years and working for oman air as an aircraft engineer,I am eager to travel to China to visit China with my family .
1-How can i apply to get visit visa for me and family?
2-How long it takes to get the visa and how much is the cost?