Talk pages are places that you can leave messages (comments/questions/etc) to a person.
There are a few tricks for formatting comments on wiki talk pages that you may want to use.
Starting a topic
Go to the talk page of the person you wish to leave a message.
Just click the add comment button at the top of the page. This creates a new section for your message.
You can then give your message a subject in the Add a title box and type your message below it.
Replying to a topic
And when you want to reply to someone's message, click the Edit button next to subject heading. This will put the subject in the edit history so it is easier to tell what you replied to.
You can add your signature with three tildes ~~~~, add a datestamp at the end of the message by putting four tildes, ~~~~. If you want to enter your own name but sign with a time and date stamp, putting five tildes will just that, ~~~~~.
To indent you text put a colon ":" at the beginning of the line. Use multiple colons to indent further. You will need to put a colon on the new line to indent it.
Making a paragraph/line bold
If you want to make a paragrph bold, use a semi colon ";" at the start of the line/paragraph.
You can also do a line break without putting in a blank line by using the html tag <br>.