How to I get to use the greyed out items between lessons? like 'animals' or 'food'
Can you post a screenshot?
Greyed out lessons that are after your latest active lesson just aren't available yet because you haven't finished the prerequisite lessons. But there shouldn't be any gray lessons in between blocks of "active" or gold lessons.
So a picture might help.
Ok, so see how Basics 2 has "0/5" next to it? There are five lessons you have to complete first.
Units you have completed will have that "strength meter" next to it (Basics I and Phrases are currently gold). If a unit is colored but doesn't have a strength meter, that means you need to open that unit and scroll to the right in search of the lesson(s) you haven't done yet.
In this screenshot, all the units are completed. Adjectives, Possessives and Plurals all are completed but need to be practiced again, aka "regilded." Food and Animals have been practiced more recently and so are gold.