This section of Old Ponale Street starts at a junction with Pregrasina. This is a tarred road, hence the easy rating.
Stay right and follow the traffic-closed old road with some bends into Ledro-Valley. There is no descent, but maybe your gps-device will show you descending due to the sheer rocks surrounding you. This road ends where the new Street SS240 (from Riva to Ledro-Valley) leaves the long tunnel.
After ending this uphill section, be careful, there's a lot of traffic on SS240! It's not far to the next trail, however, it's less than 500m.