Hi,
If you go for the CoffeeCup VSD (Visual Site designer), you need to start from scratch, because it's not possible to import an existing site into that programme.
If you are not scared away from having to learn some html, you could try the CoffeeCup Html Editor, into which you actually can import a site.
As for templates, both programmes come with some templates, and it is possible to buy more from our CC Theme store,
https://www.coffeecup.com/store/themes/
If you go for VSD, you would have to go for a template especially designed for that prog. As for the HTML Editor you can take any free template you might find out there somewhere. Pictures can be changed out, background and colour schemes too, so I'm sure, if you don't find a ready made landscaping theme, you can chose one you like the layout of and just adapt it. Of course you can also do without a template, just try!
Since this will be your first attempt at a website, you may want to experiment a bit with the two progs before you decide on which you want to use. Download a trial version of either and play around with them for some time. They are fully functional, but of course they will cease to work after the trial period has expired. (and when you buy a registered version, don't forget to uninstall the trial version first! A lot of people forget that, and then they run into trouble with the programme and think it's not working. Just a hint...)