Wikipedia gives you two options for editing. The Visual Editor lets you edit the text on the screen just as it appears on a Wikipedia page, similar to other word processing applications and websites. Source editing lets you see the underlying Wikicode, which resembles HTML.

When you're using the Visual Editor, you can switch to source editing (and back to visual editing) by clicking the pencil icon at the top right.

The Visual Editor simplifies the process of adding text, citing sources, linking to other Wikipedia articles, and formatting your article. Wiki Education highly recommends you use the Visual Editor when writing Wikipedia articles. However, this tool is only available for articles. To talk to other Wikipedians on Talk pages, you'll use Wikicode.