OK, three key points before I actually get to answering your question:
First, "CPU % Busy" is a crap metric. Ignore it.
If this value is less than 100% your server is under-utilized (the CPU is idle doing nothing).
Second, and similarly, "Load Average" isn't a great metric (though it's better than "CPU % Busy").
Load Average <= number of cores in the server is a good rule of thumb, but if the load average is 10000 and the system is performing well what do you care?
Third, DirectAdmin, cPanel, and all of their ilk are terrible. They're like keeping the training wheels on your bike forever: You'll never learn how to ride if you don't take them off.
You will likely not be able to really optimize your system while using DirectAdmin or any other "control panel" - start planning to get rid of it (or if you can't, at least turn off its nuisance alerting and implement proper monitoring software - something that alerts on performance rather than "Oh hey the server looks a little busy").
Bottom line: If your system is performing well enough to meet your needs don't mess with it.
If it isn't performing well (or you want to mess with it anyway) read the documentation that Lothar pointed you to and make sure you understand what each parameter you're changing does.
(The kind of cookbook cargo-cult system administration that "Linux Stuffs" article you linked to is perpetuating with their suggested values is wrongheaded: Most of the advice is generally good, but you need to go read the Apache Project's documentation for each of those parameters, thoroughly understand what they do, and determine what the right value is for your environment, otherwise you're not really being a sysadmin, you're just pushing buttons.)
You should also refer to this Server Fault question on capacity planning for web sites for some general guidance - Remember: the only way to know how a machine will perform under load is to test it.