I just use the software Gisto to write my code and save them (not open), it seemed like a part of github and what you wrote on gisto will also keep in gist. But I heard that github just free for open source project, since as a beginner for me, I just use gisto like a useful notebook, I'm not sure it will charge or not? Thanks!
Gisto co-creator here. To answer some questions and provide some clarity:
Gisto is a free and open source software project
Gisto is NOT part of GitHub (and not associated with GitHub in any way), it is independent project using GitHub gist service as a medium via GitHub API.
Gisto is free to use and no charging will take place
Regarding the privacy concerns please advise the link kindly provided by @HaWe above https://help.github.com/articles/about-gists/#secret-gists
If you have more questions, see Gisto page https://www.gisto.org or just contact us