Type in normal links just as you would. You an either add the markup your self or simply paste the link and it will be autolinked for you.
The part I want to spend a minute on is the Citadel custom linking that we created to make it a little easier to link to stuff. A truncated version of this is available on the actual submission page so you don't have to memorize anything, it is all right there for reference.
[Sub Name] : Name must be exactly the same as title of what you are linking to. The link created will link to that Sub using the Sub Name as the link.
[Sub Name|other text] : Name must be exactly the same as title of what you are linking to but other text can be anything you want used as the actual link shown. This will link to Sub Name while using "other text" as the actual link you click on.
[numerical ID|other text] : Similiar to previous link option but foolproof. Can't usually mess upan exact number. Simply use the submissions numerical ID in the firstpart and the actual submission title or another description test in thesecond part. It will link to the numerical ID you inputted and use "other text" as the link you click on.
Comment/Submission Idea Linking
[382#2083|other text] : Comments AND Ideas: In eachidea/comment is the exact code you need to link directly back to it. It will look very similiar to the first portion shown (382#2083). Thisallows you to directly link to that particular idea/comment if you referenceit. So if there is a great comment or idea that drove you to create a submission, you can link back so that they will go directly to it. As always, the "other text" is what will be the clickable link taking you to the comment.
[#2083|text] : Same as above but itcan ONLY be used on the same page as the idea/comment. You could use thisshorter version if you built a table of contents for ideas added to thesame sub.
Note: Those that like making tables of contents, when you edit a submission with many Ideas on it, there is an automated list of premade links for you to copy and paste to quicken your ToC creation. You would only have to update the "text" part. Scroll under the "Submit Post" button to see other options that are available when editing subs.
Independent Idea Linking
[idea#4565|other text] : Will create a link to the single idea using the text you provide. Each idea has the exact link as shown posted in it for easy copy/paste and usage in your submissions.
[freetext|Actual word] : "freetext" must be put in exactly as written to identify it as a freetext link. The "Actual word" must be exactly the same as freetext that you want to link to. "Actual Word" will be the link to click on as well as the freetext page that you will be directed to.