Not much to tell you the truth. You can always get pre-made templates. Now... If you want to design a site from scratch you need a lot of knowledge actually. HTML, CSS and JS are the basics Cheers
Yes, for the HTML you must know all the basic property how work. Also, you can find tutorials and ready templates from google as well.
Start with pre-made templates and use http://www.w3schools.com/tags/default.asp for help, it shoudn't be a problem.
Definitely for a good web designing it is must to have a good knowledge of HTML. Without prior knowledge of html it is like just building simple layout of the page without using the features of html.
HTML is just a basic language to start with and is quite easy to learn. To be able to create a website template you need to know HTML structure , how to divide your pages elements (HTML tags, classes, ids) and how to style your creations. To style a template is absolutely necessarily to have some knowledge about css . Most times css and HTML will not be enough to obtain what you want and you will need to learn some JavaScript to validate forms, add effects , integrate JQuery plugins and more. If you want to go even further in webdesign and create more complex things, like WordPress, Joomla, Drupal and any CMS themes, you need to learn some PHP, how to insert and get data from a database and more. Conclusion is: HTML is not the harder language to learn , but without other, especially css and javascript you can't achieve professional results.