The RF transmitter can be directly soldered to the GND-VIN-A3 pinouts on the left of the Ethernet jack (the pinouts are labeled ‘RF’).
There are no direct pinouts for the DHT22 sensor, however, you can use any of the available pins in the general pinout area (above the LCD) to interface with DHT22. All you need is VCC, GND, and any available data pin, for example IN2.
When programming in Arduino, you need to provide the digital pin number. I am listing the digital pin numbers below:
A3 : 28
IN2: 2
A05: 26
A06: 25
A07: 24
RXD: 8
TXD: 9