TWiki is linking topics automatically, provided you give a WikiTopic a name that follows the WikiNotation. It is a sequence of:

Good examples for topic names:

Bad examples for topic names:

Sometimes you have to be creative to find a good name for a WikiTopic. For example, if you want to create a topic about the year 2000 problem, you could go for FixY2K? or YearTwoK? or YearTwoThousand?, but not Year2K or Y2K or Y2000 as a topic name.