Or you can create a repository, then create issues where you explain your ideas and then here you can start a new topic on Project Development Help and Advice to get help or collaborators.
Tagging an issue with "Help Wanted" is a way to attract attention. As Wabri mentioned, creating a repository and writing some issues are the first steps.
Please follow-up to let us know how you made out. For good karma, mark a reply as the answer if it helped!