Whats the initiation to become a freemason? Why is their society so secretive? What are they trying to hide?

Are there secrets in their masonic symbols? If so why are they displayed so openly in plain sight? On buildings, clothing and on their rings? Earlier on I approached a gentlemen who looked like a freemason in my opinion (Middle aged upper class male in a suit with a brief case), I said to the gentlemen that I had seen him at the Lodge, he denied this but i could tell he was clearly lying (he looked bewildered) , i then asked to shake his hand and he said he refused to do so.... What does this mean?