You can park at the Mary River Cod Park and start the trail from here.
[text taken from Noosa Council website]
The Noosa Trail Network is made up of eight scenic hinterland trails suitable for walking, horse riding or mountain biking. The spectacular countryside trails are well signposted, and vary in length and difficulty. Detailed trail information and maps are available:
The trail passes through the national park, state forest, private property, council parks and road reserves. Trail bike riders, 4WDs and dogs are not permitted on many sections of the trails.