"In a storylet?"

Hi. I’m a new player so maybe this should be obvious, but why does it tell me in red text I’m &quotin a storylet&quot therefore can’t use a lot of items in my inventory when I hover over them? Do I have to finish all the stories under my &quotstory&quot tab to be able to use these things?

It’s just a warning that you are currently in a storylet. You can still use them whenever they’re green bordered (a red border means you can’t in that location). You only have to worry about it after you’ve summoned a card using Write Letters in your Lodgings, or if you already played an option on a card and it brought you back to that card afterwards. Clicking an item at those times would cause you to lose that opportunity, and you’d either have to wait for it to show up or summon it again.
edited by Sara Hysaro on 7/13/2014

It wasn’t entirely obvious when I was new, but Fallen London is structured kind of like partitions, folders and files on a hard drive:

Partition = Area (Lodgings, Ladybones Road, Spite, Veilgarden, Watchmaker’s Hill)
Folder = Storylet (the options listed directly in an area, and also cards that you draw)
File = Choice that can have some effect before returning you to the Area you’re in (or to your Myself tab)

Clicking on a usable item brings you to that item’s own storylet with choices, taking you away from whichever storylet you might have been in when you went to your Myself tab. So that is why that happens: Usable items are like storylets themselves.