There are two ways to share building blocks:
Via blocks.bitreactive.com. This is the simplest way to share finished applications or libraries with others. You can update the shared content at any time, usually if you have a new stable version. When using the free plan, you may be required to share some of your blocks in this way. You can share
Via Git. You can share all files via Git, to give others detailed control over the development of blocks.
You can also combine these two ways of sharing. For instance, you can collaborate with colleagues using Git, and share your libraries with other developers in the world using blocks.bitreactive.com, whenever you have a new stable version.
Sharing via blocks.bitreactive.com is further explained here.
When you work together on a project or library via Git, consider the following tips:
Do not work on the same block at the same time. It may be difficult to merge changes on the graphical model that are stored in the *.uml file of the block.
Use separate Git repositories for the different projects and libraries.
The following articles cover sharing via Git: