THIS PROBLEM IS SOLVED NOW
I'm trying to deploy my already created django app. I used virtual environment on my desktop. Now, on pythonanywhere when I try (mkvirtualenv --python=/usr/bin/python3.7 fir-virtualenv) command, It gives me error that states "The path /usr/bin/python3.7 (from --python=/usr/bin/python3.7) does not exist". This is first time I'm using pythonanywhere and I'm confused what mistake I'm making.