In Wikipedia there are two options for editing. The first one is the Visual editing which lets you edit the text on the screen just as it appears on a Wikipedia page. Another one is Source editing which lets you see the underlying Wikicode, which resembles HTML.
For beginners Visual editing is easier one to start with because there is no need to do any coding and the editing basics are very similar to any other editing platform like Wordpress etc. It simplifies the process of adding text, citing sources, linking to other Wikipedia articles, and formatting your article.
To choose between the Visual editing and Source editing just click the pencil icon at the top right of your sandbox page.
If you choose source editing as an option, you can edit a page using wiki markup. Wiki markup is Wikipedia's own formatting language, also called wikitext. It consists of the syntax and keywords used by the MediaWiki software to format a page.
Wiki markup can initially seem intimidating and as a beginner it is more than enough for you to use visual editing instead. However, to use a Talk page or make changes in source editing mode, you'll need to learn a little Wikicode.
Here are the basics:
'''bold'''
= bold
[[bold]]
= bold
To add links, use 2 brackets on each side of the words you want to link to an entry. That link to the article Bold will redirect you to Emphasis (typography). To link to an article with a different name than the text, put a |
(a “pipe”, inserted with ''shift + \'' on most keyboards) in between the code and the word you want to appear on the page. Like this:
[[boldness|bold]]
= bold (with the link to Boldness)
If you would like to learn how to use source editor, you can check the link in Guides and Cheat Sheets for more information.