With WordPress you can build your website from scratch, however I’d suggest to take a more professional approach and start from the basics, which is website planning.
First you need to know what should be the main objective of your website. Try to identify who will be the visitors and what would you like to show/sell/learn them. Research is a good thing. Visit a few similar websites/blogs and compare them with your idea.
Next step is to visualize the skeletal structure of your website. Instead of using a flipchart, or paper and pen, use a website planning app.