Ok that is what I thought you meant but wanted to make sure. First you are going to write them down. Just do points. Now if you have a scene in your head just write it. DO NOT WORRY about spelling mistakes, missing words, or grammar. OMG if you only seen my extremely rough drafts you would be like WTF lol. Get that scene out of your head and on paper. If you just have ideas then get them down all on paper. Once you are done read what you have then set up what order you may want them in. (I do not do this but a lot of people do as well as published authors) Don't worry you will most likely change things as you go. Also I sometimes write a scene that is later in the book, actually I do this a lot. Just save your work so when you are ready you add it in where you want it. On the days you are either blocked or (like me) have to many ideas flying in your head just write something else. Sometimes you have to get rid of the noise in your head to concentrate on what you really want to work on. For example I just wrote a few pages for a chapter that I am not even at. Now I have that out of the way I can concentrate on where I was. If I get stuck again I will go to one of the other 2 books I have on the go.
Oh what I also do when I am writing down points for a new book is I put a big star on the ones I want for sure. I also drag my 21 year old into my room and bounce ideas off her. Having her to bounce ideas off of helps get the creativity juices flowing as well as gives me a better handle on where I want to go.
I hope that helps. If you have any other questions I will do my best to help
