Running out of disk space on new clean install of 7

First, I am not a pro by any means. I just got my computer back from a clean install of 7. There was nothing on it, that I know of, when I got it back. I installed, NIS, Malwarebytes, CCleaner, Dropbox, USB safely remove, WinZip, Firefox and Foxit Reader. I now seem to have less space on my hard drive than I did before the clean install. How can I tell what is taking up all the space? I also installed Office 365 and Adobe Photoshop cc which I had before. Had all the above and more before but now I have less room. I am stumped.

Thanks Brink, I will check it out. I can't believe that I am already down to 37% and I just installed the programs I always use nothing else. I am almost afraid to download anything else. thank again.

Brink: I just wanted to say thank you again. I downloaded the portable WizTree and it found that it
was Dropbox that was the trouble. They uploaded in Camera uploads, all of my photos from my portable
hard drive. Just went in and deleted them and now I have 167 GB of space left.