you can change your conky settings in a file called .conkyrc (/home/username/.conkyrc)
the file isn't created by default but you can find a sample configuration file on your computer.
I'm using Debian, and my sample file to get you started in:
You'll notice a whole ton of settings, and then a TEXT label. Everything after that appears in your conky file
you asked specifically for cpu use:
will print the current usage of your cpu
will print the current frequency your cpu is running at
but there are tons of features - you can even pipe information through bash scripts or python scripts that perform a calculation that results in a number between 0 and 100 and link to it to create your own custom bars.
you can also find a list of variables, and settings you can tweak
you can also find a list of variables to tweak for the *most current* version of conky here:
dig around the website a bit, there is a ton of documentation.
If it's not in exactly the same location you can search for it.
sudo updatedb #to update your search database