CDO

i have a file for global wind data (u and v component together) for July month from 1980-2016 at 850 and 200hPa levels and i now i want to find out trend for this variable. though the cdo trend code seems simple but i think i am missing or making a mistake somewhere. Moreover, i also intend to get trend for specific humidity with same spatial and temporal scales. Data is acquired from Copernicus (https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-pressure-levels-monthly-means?tab=form) repository. !!

Any help would be welcomed

Regards
Karim