You are using Debian, you installed wireshark, launched it and found that there was no interface (under interface list) for wireshark to capture; you checked /etc/group and did not find a group known as wireshark, then it is most likely libpcap-dev not installed.
sudo apt-get install libpcap-dev
sudo dpkg-reconfigure wireshark-common. A ncurse screen appears asking if you allow non-root user to use wireshark to sniff, choose yes. The group wireshark should appear.
Check /etc/group, you should see a group known as wireshark, then add your username into group wireshark:
sudo gpasswd -a username wireshark.
logout and login you desktop environment and launch wireshark again, you should see interface/s under interface list.