That's not a silly question at all! It's a good idea to know what should go into an article and how it should look before you start. Your sandbox is an excellent place to draft an article and practice editing.
Starting a draft
Go to your sandbox and start to edit. Just make sure that you're logged in! If you're not, then you will end up editing an IP address's sandbox, making it very easy to lose your work. Remember, a sandbox is just a draft space on Wikipedia. You can create as many sandboxes as you like.

Creating a framework
Sometimes when you're starting a new article it can be helpful to put up a general framework. Don't worry if the article ends up looking slightly different - not all articles look the same. For this example I'm going to use a book article's general framework: the lead, synopsis/plot, development, reception, awards, and a reference section. After you're done setting this up you can add an infobox to the article as well.

Wiki Education resources
For tips about what to include in your article, check out our subject specific handouts by topic:
From here you can start adding information to your article and flesh it out. Of course if you ever need any help, you can always talk to your Wikipedia experts for advice!