Under the INSERT command (top tool bar) use the INSERT SYNTH function and it should be in the list.
Choose it and it will load. On the interface that shows up, there is a horizontal menu tree.... simply select the main instrument on the left....such as BASS, then narrow that down in the center column, and the right side column will be a list of all the available individual instrument samples in that category..... double click and that one will load. The GUI remains, and if the sound is not to your liking, simply click another from the right side column or start over to change to something totally different.
As you purchase and install new sound packs for CSC, the new sounds will automatically populate the correct categories and become available.