The journals are simply another forum just like the one you are in right now - there is absolutely no difference except in how everyone has agreed to use that forum.

Go the the My Journal / Bootcamp forum which is listed near the end of the forums. The sub-forums are grouped by the first letter of the USER name to keep finding a particular journal relatively simple.

To start a journal, just start a new thread. That's your journal. To find another person's journal, just find a thread started by that person. It's that simple. There's a sticky that explains things in more detail at the top of every journal forum.

Hope that helps.