Installing Dune with the help of Opam

I have somehow managed to install Opam on MSYS2 on Windows.When I open the MSYS2 MING64 (the blue one) shell and enter

opam --version

it tells me that it is installed.

When I run

opam install dune

, that command worked the first time and now it says

[NOTE] Package dune is already installed (current version is 3.5.0).

However if I then want to launch dune with

dune init proj myfirstocamlproject

it says

bash : dune : command not found

I followed also the tutorial https://opam.ocaml.org/doc/Usage.htmland ran the command

opam init

It tells me in the end

User configuration:  C:/Software/msys64/home/imelf/.profile is already up-to-date.[NOTE] Make sure that C:/Software/msys64/home/imelf/.profile is well sourced in your ~/.bashrc.

What should it mean? Where is this file ~/.bashrc. and what does the tilde mean?

What do I do wrong?