There are no real limitations, nor prescriptions: every Sharer decides autonomously what to upload as long as s/he believes that the sharing has a social dimension that can be useful to the community of readers and the society at large.
You can write about your family, your neighbor, your day at work or school or you can write about ideas related to a certain issues with a social dimension: education, health, livelihoods, human development, volunteerism etc.
You can share in a technical way or in a more informal manner, even through a story. Everybody has a peculiar style and way of expression. Just follow your instincts and share it.
Note: For the time being S4G accepts also reposting and pieces published on other media. In this case it is up to the Sharer to acknowledge the original source. We hope in a near future to generate enough users to be able to accept only exclusive sharings.