In response I used this french site to configure mine:
https://medium.com/@straumat/tutorial-miner-des-bitcoins-a-la-maison-avec-un-raspberry-pi-c1631bb11a06 Just do a translation and you should be OK
cd bfgminer
./autogen.sh
sudo chmod +x ./configure
sudo ./configure CFLAGS=”-O3" --enable-scrypt
sudo make
sudo make install
sudo ldconfig
If you dont want it to start when you boot the RPI3 skip "Étape 5"/ Step 5
like the other said just open a terminal and put
cd /bfgminer
bfgminer -o xxxxxx -u user.worker -p 123