You already understand RTOS concepts (Semaphores, Message Queues) from Zephyr or ThreadX, or you need extensive POSIX or networking coverage (look for FreeRTOS+TCP PDF separately).
: Offers five different heap allocation schemes to balance speed and memory fragmentation. Recommended FreeRTOS PDF Resources freertos tutorial pdf
Flash an LED using a task, then use a Queue to send a "Toggle" command from a second task. Read the PDF section on "Queue Send from ISR" to understand critical sections. You already understand RTOS concepts (Semaphores