In response to your very cryptic question I'm assuming you're using an STM32 as the main controller and an ESP8266 with default AT firmware and want to use AT commands sent by the STM to do something, right?
If my assumption is correct, I'm afraid you wont be getting a lot of response on this forum, since what you're actually asking is an example for an STM and though there are people here that also have knowledge or are using STMs, I think you'd have more luck on a Microchip STM forum.
Apart from that: in my opinion (and I think a lot of ESP user will agree with me) you don't want to use the default AT firmware the ESP comes shipped with, because it's very limited in it's use and would make things more difficult than needs to be: not only you will have to get the STM and ESP work together, you'll also have to implement the AT communication protocol into the code of your STM, since you're basically only using the ESP as a (telephone-like) modem.
Don't forget the ESP is also just a controller. like the STM (though not ARM based), with an internally added WiFi stack and hardware: you can program the ESP any way you like, using a multitude of programming languages and let it do the thing it's best at: transferring data wirelessly in any way of form you want (including sending things to a server).
My suggestion would be to pick any language you'd like (Arduino is pretty populair) and try out a few of the many examples to chose from.
Also you might want to catch up and do some reading, regarding programming the ESP.
After that you can decide if you still want to use the STM -> ESP route or want to create a one controller (ESP only) solution; the ESP is powerful enough for most tasks.
There's nothing wrong with the idea of dividing tasks, let the ESP handle all the communication and the STM do the reading/measuring/calculating, depending on your project.
But... as said: with most projects the ESP on its own is powerful enough to do all task by itself.
The choice is yours, once you know what your options are.