Select your Community space, then
Thanks for sharing your feedback about Esri Community, @JMOceanographic. Our team strives to make it both an intuitive and helpful space, and messages like yours are something we pay attention to.
I hope Dan's pointing out of the "Create A Post" button location makes things easier for you moving forward, but know that we're here to help if you have any other questions. Two things that may prove useful: 1. If there's an Esri Product (or products) you're particularly focused on, we can point you towards that location to bookmark for easy access later, and 2. feel encouraged to browse our Community Help Documents for how-to's and guidance on how to use Community.
All the best!