Upwork: This website offers a great marketplace for selling just about any professional service. You don't need a merchant account, website of your own or anything else for that matter. All you need to do is be able to provide a high-quality service at a reasonable price. But be informed, you will have to compete with many others that are constantly bidding on open jobs.
Hypertext Markup Language (HTML) is the standard markup language for creating web pages and web applications. This step is important to keep your costs down and still get what you want. If you're not familiar with basic HTML and basic concepts about running a website, invest in the time to learn; it will be well worth the outlay in the long run. Even if the site is basically a template for you to use, you're still going to need to know how to insert images, create hyperlinks, and do some text formatting.
I have a free WordPress website with 1000-2000 visitors/month. I was trying to place Amazon Affiliate ad links last night and failed/flailed mightily. I would paste the links into my posts in the HTML mode, switch to Visual mode, and could see the image. However, every time I tried to save or update the post, the image reverted to the gangly hyperlink. As some suggested, I tried cleaning the links of any formatting from the copy and paste with text edit. No dice.