I like a wordpress design. Can I copy it? How to do it and can it work?
How do you mean? You’ve seen a modified theme or a theme designed specifically for one site?
I mean a theme designed specifically for one site and its a original theme.
You may be able to determine if the theme was purchased or a free theme. In that case you can get it from the same place and install it on your Wordpress site. If it is a custom Wordpress theme, you can’t copy and use it legally although it probably would be possible. Maybe just email the site owner and ask them for details about their theme.
Check the source code. The theme name may be in the header.
Most themes don’t come with PSD, but if it does you could alter the design in Photoshop or just modify the code as long as it is a free theme or one you paid for.
View the page source code and look for a link called in the header that looks something like this: [website URL]/wp-content/themes/maya/style.css
If it is Wordpress and running a theme it will call various stylesheets etc and once you see the pattern you will be able to see the folder that the style sits in. You can then google the name with wordpress theme and see if anything pops up. There are thousands of themes but many are not expensive to buy and you tend to get good options with many of the commercial ones.
That’s what I said, but you put it far more eloquently 
Yea sorry bout that. I just never know how much people know. I figure it’s better to have the steps in case someone with lesser knowledge hits the same problem.