Take a look at this web page which gives instructions on how to add a directory to PATH in Linux https://linuxize.com/post/how-to-add-directory-to-path-in-linux. For example,
for only one account:
export PATH="/usr/NX/bin:$PATH" >> ~/.bashrc
for global (need to be done as root):
export PATH="/usr/NX/bin:$PATH" >> /etc/bash.bashrc
You could use aliases (edit the same files based on whether you want to set globally or locally, and add these lines):
alias nxserver=’/etc/NX/nxserver’
alias sudonxserver=’sudo /etc/NX/nxserver’
alias nxplayer=’/usr/NX/bin/nxplayer’