Firstly, you should turn on your blue-tooth on pc: select the Start button, and type Bluetooth. Select Bluetooth settings. If Bluetooth is off, turn it on, select your iphone7+.
Then, To transfer from your phone to your PC,Look for the Bluetooth icon and then select your PC as the device you want to send to. Windows will probably request confirmation and allow you to choose the location to store the file.
If this can not work, you can choose other convenient ways to transfer your photos from phone to pc.
1.Email and cloud storage;
2.Wifi direct(this may be a little hard to setup).