adware removal

My iMac [OSX 10.9.5 ] was hit by adware. Sought help at Apple Store. Techie advised me to download Adware Medic from 'the safe apple.'

I was able to download the file on my MacBook Pro to a jump drive. Then transferred the file to my iMac. The only instructions shown when I opened the file was this graphic (see screen shot below). I dragged the file to the applications folder as directed. I clicked the file to open it....same graphic appeared. There was no instructions to run a scan. Please advise.