Reactive Blocks is a plugin to Eclipse. It is maintained by Bitreactive, a spin-off company out of NTNU. All installation instructions are here.
To sign up, you register with your Facebook or Google account. Reactive Blocks has a free version that you get by default, but as a student you can also receive an educational license. For that, join a specific team on blocks.bitreactive.com. Usually this team has the name of your course, followed by the current year. (Ask your course instructor.)
The best place to get support for questions regarding Reactive Blocks is really the support page. Feel free to ask your questions there, either in the forum or by email.
The documentation is here. It contains the reference for the tool and also a number of tutorials on different levels. Should you have any problems with the tutorials listed from Bitreactive, feel free to ask the support!
We created the team NTNU IoT Recipes to collect building blocks used in the recipes. Join the team to get access to them.