I don’t see a microcontroller on that image. You can’t connect a PIC microcontroller Tx and Rx pins to Max232 to control a GSM module. You only use the MAX232 if you are going to control your GSM from a Computer.
Before using circuit found on internet, try to read and understand them, you might damage your devices.
If you want to control it form a microcontroller only a voltage level translator is required.