Trying to install CUDA on my RTX-2080 and running into all kind of troubles

I have recently installed Ubuntu 20.04 alongside windows. I have RTX 2080 graphic card and I am trying to use the GPU version of TensorFlow or other GPU-based python modules.
In my terminal when I type:
test@test:~$ nvidia-smi
output :
NVIDIA-SMI 460.80 Driver Version: 460.80 CUDA Version: 11.2
But when I check
test@test:~$ whereis cuda
It shows me nothing. What is weird is that it did show me that CUDA Version: 11.2 in my previous command and when I check the folder /usr/local/ I don’t see CUDA folder.
And when I do
test@test:~$ whereis nvcc

I am trying to follow the procedure outlined in the following website:

I am not sure why it shows CUDA version 11.2 and does not show where CUDA is.

Please tell me how I can solve this problem and proceed with the installation of CUDA and cuDNN.
I appreciate any help.
Many thanks