That library is intended for usage a DHT22 sensor which allow measure a temperature and humidity. DHT22 is 1wire sensor which require to use pin as input and output like also it require a microsecond delay, because that sensor works with very specific timings. To create a microsecond delay is used TIM3.
Firs of all is require to set pin which is connected to the sensor as output or input. Then copy library files to the project directory and include DHT22.h. That library is simply to use, just call init function:
void DHT22_Init(GPIO_TypeDef* Port, uint16_t Pin);
Example:
DHT22_Init(GPIOA, GPIO_PIN_9);
To read data from sensor use
uint8_t DHT22_Get_Data(uint16_t *Temp,uint16_t *Hum);
Example:
uint16_t Temp,RH
DHT22_Get_Data(&Temp, &RH);