Lua is a lightweight programming language that is particularly suited for embedding within other software. The software used by Wikipedia, called MediaWiki, has an extension (called Scribunto) that provides a version of Lua that can be used within Wikipedia pages.

1. Create a Wikipedia account. See https://en.wikipedia.org/wiki/Wikipedia:Why_create_an_account%3F . Adding an email address allows you to reset your password if you forget it.
2. Use the link at the top right of your page that has your username to create / edit your user page. Add some text, noting that you’re taking part in GCI, but don’t add personal information. Preview your edit and save it.
3. Use the link at the top right of your page to create your sandbox. Type some text, preview it and save it. Remember that what you type can potentially be seen by anybody!
4. Read about Scribunto, the Lua implementation embedded in Wikimedia software.
5. Create an empty sandbox module for yourself as a subfolder of https://en.wikipedia.org/wiki/Module:Sandbox . For example, if your user name is Joe Bloggs, then create your module at https://en.wikipedia.org/wiki/Module:Sandbox/Joe_Bloggs . Note that any spaces need to be converted to underscores, _. This is called "url encoding".
6. In your sandbox, add a line of text starting with two hyphens: -- After the two hyphens, type your username followed by Google Code-in 2017, Introduction to Lua in Wikipedia. Text beginning with two hyphens is used in Lua to designate a comment.