Inserting a link to a specific section of an article is fairly easy to do, though finding directions on how to do it is a bit difficult for some reason. Perhaps that's why this question comes up frequently.
The short answer is that you do it with a "#"
Here's the format:
[[NameOfArticle#SubsectionName]]
If you click the link set up in this way you will be taken to the subsection on the page of corresponding article.
Here's an example: How do I insert a link to a specific subsection of an article?#Section 3
Section 1[]
This is empty filler
Section 2[]
More filler
Section 3[]
This is the target of the example. You can use this technique to help readers navigate to a specific portion of the page they are currently on, (as is done in this example), but you can also use it to take them to section of a totally separate page.