Click on "Edit" at the top of an article. Then place double square brackets around the topic you want to link to.
For example: [[pear]]
For the plural write this: [[pear]]s
If you want to create a link to a section of an article (for example "Cultivation" of the "pear" article) place an internal hyperlink "Pear#Cultivation" separated by a vertical bar ( "|" ).
For example: [[Pear#Cultivation|cultivation of pears]]
which will look like this:
