Finally Getting Started Here

I really do want to start using this account for writing fics, but I have a minor issue. I can picture certain scenarios in my head when creating a story and I can imagine how it plays out, but I don't know exactly the right way to put it into words without it sounding ameteurish. I guess this is why a lot of the bigger writers here have a team helping them write the story, so that may be one option of what I may end up doing. Another idea is I could just post my stories and post and/or repost if I need to change something in some of the chapters
It's so frustrating; all these ideas in my head and no way for me to harness them properly. Does anyone out there have any ideas for me?