Once you've got your domain name registered and a hosting account and email set up, your next step is to build a website.
You've got some choices...
you can often build a one page site for free or for a nominal cost through the same Internet company that you got your cheap domain name and other services from.
However, if you want more than a landing page, you'll need to explore other options.
First, determine the size of the website you'll need.
You may only need what is frequently called a brochure site - a small site that has a few pages of information and a contact form.
If you are selling products online, you'll need a larger site that can feature individual products and have ecommerce functionality.
You may want to add a blog to your site, or even a forum where others can interact.
Many people are now opting to use WordPress to build their websites.
Although it was originally used solely for blogs, with its current functionality and the use of plugins a huge number of businesses are now using WordPress for their primary (static) site, with the option of easily including a blog on the same site.
WordPress is free, and there are innumerable free tutorials on how to set up and use WordPress, as well as thousands of free templates and a large number of plugins available.
Professionally designed templates with added features cost less than $100.
If you don't feel up to creating your own site, find websites that you like and contact the designer (check for a link at the bottom of the page).
Ask others who they recommend - you may find that you can get a website created for a very reasonable price.
Much will depend on how much original design work is needed, the number of pages necessary, and how much functionality is required.