Something I learned is that if you want to make money with your hobby site you have to create content, content other people would like to read like tutorials, reviews, or your opinions. Once you have a constant stream of content going in, you'll have a constant stream of visitors visiting, and then you can start selling off ad space. Getting a domain name is important because its basically your brand name on the internet, and $7-9/year investment isn't bad especially since you already have quality free hosting (1&1 hosting charges $4 a month just for hosting). The main trick here is getting people interested in your site, and you need content to get them interested.
Another tip, most new website owners almost always put advertisement placeholders on their website or web design, this is a bad mistake, design your website without advertisements, when the time comes you can redesign the website to support advertisements.