change terminal between 2 & 3

I will arrive from Dubai in (PEK Terminal 3) this is first ticket

transiting less than 24 hours at airport

and my next flight "within 24hours from first flight above" to TIJ airport (Mexico) departing form (PEK Terminal 2). this is the 2nd ticket.

I know that i dont need visa for transiting within 24hours but in my case there is terminal change, so what is steps for this ??? do i need transit visa ?? if not how can transfer from T3 to T2 ??