LOL I know what you mean. Every time I post it's a struggle!
It's pretty easy to track, when you're reading an entry, around the same place where you can save it to your memories there should be something that says "track" or "track this" (or there will be a symbol that looks like a push pin) and it will lead you to a screen that asks you what it is about that journal you want to track. You can be notified every time that person posts anything, or be notified if they post something with a particular title.
Hope that helps! I'm not great with giving instructions...