WordPress is a great tool for beginners at web design – you have access to millions of free themes to use on your wordpress site, which give your site a good layout, dummy content and examples of how you can use the site.
Choosing a theme should first come down to the intended purpose of the site – if you are planning to form an ecommerce site where you sell your products, you will need to find a theme which works well with ecommerce functionality. Again, if you have a portfolio, perhaps a photography business, you will want a theme which displays images in a nice way which your readers and customers will find attractive.
It is worth searching around through the themes to find the right one, and you can use filters in the search to narrow it down to find what you need. Filter the search by theme type, colours used, customisation options and more. This is a great way to get a unique and special site for you.