Q: Installing EPSON printer - error

I bought EPSON printer and set it up as wireless on my two PCs. When I tried adding it to my Mac, it started looking for software, but it's been stuck like that for several hours. When I pressed "cancel" button, it stopped working altogether. Now I can't exit or shut the computer down. This is my first Mac and I'm not familiar with all the commands (like - for PC you can reboot or Ctrl-Alt-Del to get Task Mgr and manipulate programs). I'd appreciate any ideas. Thanks!