The document provides steps to add and use the UMC_18_CMOS library in Cadence: 1. Open Cadence Virtuoso and add the UMC_18_CMOS library by navigating to the highlighted path. 2. Create a new cell view and go to the model library setup to select the UMC spectre model library file. 3. Pick the NMOS and PMOS devices from the UMC_18_CMOS library and perform further circuit design and analysis steps as done previously with another library.