Thanks, glad to see you here! The fic index should help you find stuff, each update has a link to the next part so all you need to do is find the title you want, then keep clicking the 'next part' till you catch up to what you haven't read yet. Or, there are "tags" on the left side of the page. If you look at those and click on the "jack/sarah" ones, it'll take you to a list of each entry I've made about thse two.

LJ can be very confusing to someone new, I kow. Just keep trying, keep experimenting, and ask questions all the time! You'll get there!