Move it to a recognized Folder. I recommend making a folder in [C:/] named "Test"
Open CMD, it can be found in [C:\Windows\system32] named as "cmd.exe"
Run it as an administrator. PLEASE READ THE FOLLOWING CAREFULLY!. To run as Administrator, right click on CMD and boom.
Type in the following in Order, assuming you moved FFMPEG to that a folder named "Test" in your C:/ drive and that you renamed the video as "Epi".
ffmpeg -i Epi.mp4 -r 0.5 Name-%04d.png
6. The above program would generate images for every 2 seconds, if you want to increase it, [x = 1/n] is the formula where 'n' is the seconds gap you seek and x is the value you're to set after '-r'. Remember that you must add the exact extension of your video. TIP:Tab eases finding stuff.
7. Click enter and let the magic begin!
8. Don't close anything while it's extracting the frames otherwise you're gonna have to restart. Other than that, you get this.