I assume you want to share InDesign files with someone who does not have InDesign. Is that correct?
Unfortunately, the only application that can edit an InDesign file is InDesign, and for best practices, you should both have the same version. There are programs that can allow you to open an InDesign file in QuarkXPress and visa versa, but they usually introduce some errors that need to be corrected after the fact, so it's a workflow that some would advise you only use when no other option is available.
There is a program from Adobe called InCopy that is used as part of a workflow that you may want to look at.
Some editing can be done to a PDF exported from InDesign, but since it would no longer be an InDesign file, it's not really what you're asking for. Do you want advise on editable PDFs?
You need to choose File>Package
Then Zip the resulting folder - and email it to them.
The alternative is to use a service like Dropbox (both people need this) then you save this locally to your computer.
You then choose to share that folder with another person. They can work on the file and update it, as long as all images are saved in the folders that are shared.