Directories: + FreeRTOS/source contains the FreeRTOS real time kernel source code. + FreeRTOS/demo contains a pre-configured demo project for every official FreeRTOS port. + See http://www.freertos.org/a00017.html for full details of the FreeRTOS directory structure and information on locating the files you require. + FreeRTOS-Plus contains additional FreeRTOS components and third party complementary products. THESE ARE LICENSED SEPARATELY FROM FreeRTOS although all contain open source options. See the license files in each respective directory for information. + FreeRTOS-Plus/Demo contains pre-configured demo projects for the FreeRTOS-Plus components. Most demo projects run in a Windows environment using the FreeRTOS windows simulator. These are documented on the FreeRTOS web site http://www.FreeRTOS.org/plus Further readme files are contains in sub-directories as appropriate. The easiest way to use FreeRTOS is to start with one of the pre-configured demo application projects (found in the FreeRTOS/Demo directory). That way you will have the correct FreeRTOS source files included, and the correct include paths configured. Once a demo application is building and executing you can remove the demo application file, and start to add in your own application source files. See also - http://www.freertos.org/FreeRTOS-quick-start-guide.html http://www.freertos.org/FAQHelp.html