Let's say you have a library called libfoo located in /usr/local/lib and you want to link it with a node you're building called my_node. Put the following in your CMakeLists.txt:

# set the path to the library folder
link_directories(/usr/local/lib)

# link the libraries to the executable
target_link_libraries (my_node foo)

(/usr/local/lib is probably in your environment path already, so the first line might be unnecessary)