I am trying to test MongoDB and I have it all downloaded and moved into the root folder. I can navigate to the folder that holds the mongod, but when I try to run it by typi
You need to add the name of the folder that contains the command mongod into your PATH so your shell knows where to find it.
So, if mongod is in /usr/bin/freddyfrog, you would edit ~/.profile and find the line that says PATH= and edit it to look like this:
export PATH=${PATH}:/usr/bin/freddyfrog
Then login again to make it take effect.