I've just installed ClassiPress and so can give some first-hand experience. There are two levels of expertise required. The first one is basic knowledge of servers, how to FTP, how to run WordPress, how to CHMOD files and so on. Even at the most simple level, you are going to want to create your own logo and upload that to use with your installation. This will get your site up and running and then it's down to you read the documentation and watch the video tutorials to see how to do things. ClassiPress is one of the best classified ad themes when it comes to documentation and having an active support forum like this.
The second level is optional but probably desirable. You are going to want to modify it to make it do exactly what you want. I'm talking about fine-tuning here - the core functionality of being able to post ads and see them is all there right out of the box. Much of the behaviour can be amended in the CP Dashboard when logged in as a
WP administrator. You may find that it does 90% of what you want. You might even get this up to 95% or more by installing some extra plugins to make, for example, fancier registration forms. You might decide to tweak the colour scheme, change the font, remove certain elements, change some of the wording and so on. This will require some knowledge of CSS and an idea of what php file to amend. The thing is to do what is within your capabilities to do.
If you have ideas for wanting to do something, it's quite likely that somebody has thought of it before you and so you search the forums here to get ideas of how to tackle such things. It would be rare for any software to be all things to all men and we often want to tweak to fit our own ideas of how it should work. If you can't live without it doing EXACTLY what you want and you are not a regular code jockey then there are people out there willing to customise it for you, at a price of course.
The example page you posted is an example of customising the default installation to make it into what you want it to be. If you are happy with CP out of the box then you don't have to do anything like this. Besides CP is constantly being updated and things written several months ago for an earlier version may not work with the current version.
Hope that helps.
