GolamMostafa:
You proceed to help yourself; afterwards, help will come from other sources. Please, start the job --1. Collect 2 UNOs.
2. Collect 2 HC12 Modules.
3. Connect the modules with their respective UNOs as per instructions of this link.4. Test the basic functionalities of these modules using the instructions of the above-mentioned link.
5. Now, you have in your hand 2 working HC12s.
6. Now, plan your project -- decide which module (HC12-A) will be collecting data from sensors, and these data will be transmitted to other UNO via HC12-B. Are you looking for Transmission/Reception routines? They will be come in into this Forum/Thread from various sources once you start the project and show your efforts.
Good plan.
Although after step 5 and before you can move onto step 6 you need to confirm the HC12s will give you the range you want, its pointless planning the project until you know the chosen equipment will work (in a forest).