We attached the two ESCs to each motor with the 3 wires. And we attached the two power enter of both ESCs together by soldering.

We then plugged the power entry to the big blue battery. Both motors did that little noise to tell us that they werent receiving signal. SO we supposed that everything was ok.

Now the goal was to send signal. We thought that it could do it with an arduino but we thirst tried with a remote control. We found a reciever and the remote, plugged the reciever to the signal wires of the ESC but nothing happend. We tried many times but still nothing. 

We ended the sesscion by thinking that the problem was actually that this fat blue baterry was dead. So we removed it.