Application can't be opened

I ry to launch the Arduino app in my iMac and I get a notification saying

The application Arduino can't be opened

I clicked the box in info to allow it to open in 32 bit mode and am running OS X Yosemite 10.10.4

Any ideas?

did you download the right version?

We got the link for the instruction booklet. Arduino - Home

QuinnG:
We got the link for the instruction booklet. arduino.org/download

That's for the rogue/fake Arduino. They've got their own IDE, and from what I've seen posted, it doesn't seem to work very well. Use https://www.arduino.cc/en/Main/Software (download link at top of page)