Yes, for example if you want to press a button in the App and have it run some code on the Device, you must use the BLYNK_WRITE() function and match the vPins between it and the Button Widget.
The BLYNK_READ() is more used with display Widgets, set for a certain read frequency and then they periodically ask the device to update them.
Start off at the beginning with the Sketch Builder examples set for your board type
But adjust for these BLE pinouts
e.g… I think 
// define pins (varies per shield/board)
#define BLE_REQ 7
#define BLE_RDY 8
#define BLE_RST 4