From transport terminal 2 to terminal 3 of Beijing Capital Airport, do I need transport bus?

Yes, you need.

Can you give me more information? I’d like to know which bus can take me there. What time and everything useful I need to know about it. Thank you

Run Time:
06:00 ～ 23:00: Departure interval is kept within 10 minutes.
23:00 ～ 06:00: Departure interval is kept within 15 minutes.
Stops:
T1: outside Gate 7 F1
T2: outside Gate 7 F1
T3: Gate 5 F1
Route:
Gate 5 F1 of T.3 -> Departure floor of T2 -> Departure floor of T1 -> Gate 7 of Arrival floor of T2 -> Gate 7 Arrival floor of T1 -> Departure floor of T3

Thank you so much