Manually set 2.4g frequency

[benb0jangles]

hi there, please can you tell me how to manually set the transmit freq? I'm guessing the esp8266 scans for stations and ap, then tx repeatedly on those frequencies, but I would like to know what to do to set it manually. at a freq chosen between 2400-2484 MHz (802.11b/g/n). Many thanks for helping!