Welcome to CYS, Seastar. I recommend you check out the articles in the Help & Info section if you want more details on the site and how to make storygames.
I strongly recommend you write your first story on your own, it can be short but it must be complete (no broken links, no 'Demos' - the site hates those with a passion), and you can grow from there. Let your first work be bad if it needs to be (try not though), you'll learn from it.
If you have specific thoughts you want feedback on, feel free to post in the Writing Workshop. I also recommend you work on one story at a time.
Also, the site is fairly passionate, don't ask for mercy up front, and be ready to take feedback when it's given, the site can be unforgiving.
All the best for your time here, and remember: Don't feed the trolls
E: First critique: Criticize is with a 'c' and not an 's,' you may want to use a spell checker (Chrome has one inbuilt)