The kernels that you add will depend on your background and needs, but here are some of the most popular, with links that you can refer to for installation instructions:
- R: https://irkernel.github.io/
- Julia: https://github.com/JuliaLang/IJulia.jl
- JavaScript: https://github.com/n-riesco/ijavascript
The following GitHub page contains a pretty comprehensive list of available kernels: https://github.com/jupyter/jupyter/wiki/Jupyter-kernels.