Help:Linking Wikipedia pages

This is a step-by-step tutorial on how Wikidata language links will be created and maintained in the future on Wikipedia. It explains two use cases:

For more complicated cases, bots, advanced users and perhaps gadgets might help.

Step 1: Go to a page. In this example we are going to use the article "New York City draft riots". Click "add links" in the sidebar.	Step 2: A window appears. Choose the language of the page you want to add from the dropdown menu and write the title of the page. Press "Add link".
Step 3a: If the link has been found on Wikidata, you will get a window like this one. If not, you will get a window like in step 3b. Confirm the addition of the links specified by clicking "add links".	Step 3b: If the link has not been found, you will get a window like this one. Write a label and description and click "OK" to confirm.
Step 4: The link has been added to the sidebar.

Property: official website. Value: https://www.galaxyapac.com/.

Step 1a: Click "edit links" in the sidebar. This window appears. In this example we are going to add an link.	Step 1b: If there are any local interlanguage links, then they are displayed. You can copy the information needed from there.
Step 2: Choose the language of the page you want to add from the dropdown menu. In this example we are going to choose "Nederlands".	Step 3: The language code "nl" appears.
Step 4: Type the title of the article you want to add and click the "add" link next to the sitelink.	Step 5: A notification about the addition of the Dutch link is displayed. You can edit another link by reproducing steps 2-4. When you are done, click the "done" button to confirm.
Step 6: The link has been added to the sidebar.

Source