International to Domestic

Will be flying from Singapore to Beijing Capital airport T3 (PEK) via Air China and transfer to Urumqi via Air China. Our luggages will be transported from Singapore to Beijing to Urumqi via Air China. We have 3.5 hours of layover time. Please advise how to move from arrival at International terminal to take the domestic flight to Urumqi ? Thank you very much for your kind attention and help.

Yours sincerely,
Veronica.