When you give a substance to a laboratory for analysis, they also give you the Jcpds card file along with the analysis.
Of course, the Expert software, which is for X-ray diffraction analysis, also has a library you can use to do the analysis yourself.
However, I'll leave you a series of similar articles that you'll be able to follow as an example.
Studies of structural, optical, and electrical properties associated with defects in sodium-doped copper oxide (CuO/Na) nanostructures
Synthesis and Structural Characterization of Copper Oxide Nanoparticles Preparation by Two Different Sol-Gel Methods
Synthesis and characterization of CuO nanoparticles utilizing waste fish scale and exploitation of XRD peak profile analysis for approximating the structural parameters
Comparative Study on Copper Oxide Nanocrystals Synthesized by Two Precipitation Methods
Preparation and Characterization of Copper Oxide Nanoparticles Synthesized via Chemical Precipitation Method