how do I proceed to unlock the storylets that are "locked"?Is it a matter of Fate?
There’s usually some pictures next to the “go” button that tell you what you need. If you need fate, the whole box around the option will be yellow.
If it has a lock symbol that says “Impossible!” when you hover over it, it is not available to anyone but the devs. It will eventually be released to the public, but not yet.