In the short clip below, you can see that you simply need to push (no need to hold) on the podium microphone where prompted so the green light turns on and start speaking. When you are finished speaking, push on it again so that the green light turns off.
There's no need to interact with the podium's touch panel!
You don't have to get extremely close to the microphone. Doing so can cause your voice to be much too loud to the other participants. The microphone is able to pick you up clearly even when you are standing normally at the podium.