From Infogalactic: the planetary knowledge core
Introduction to tables
How and why
Review of what you've learned
Tables are a common way of displaying data. This tutorial provides a guide to making new tables and editing existing ones. For guidelines on when and how to use tables, see the Manual of Style.
The easiest way to insert a new table is using the editing toolbar which appears when you edit a page (see above). Clicking the button will open a dialog where you define what you want in your new table. Once you've chosen the number of rows and columns, the markup text for the table is inserted into the article. Then you can replace the "Example" text with the data you want to be displayed.
Tables in Wikipedia, particularly large ones, can look intimidating to edit, but the way they work is very simple.