got it to work, at least on my system

Core/Src/main.c

@@ -31,7 +31,7 @@
 
 /* Private define ------------------------------------------------------------*/
 /* USER CODE BEGIN PD */
-
+//#define LED3 LED3		//missed this part of the lecture, this program can probably still be made without it though
 /* USER CODE END PD */
 
 /* Private macro -------------------------------------------------------------*/
@@ -201,11 +201,24 @@ static void MX_GPIO_Init(void)
 }
 
 /* USER CODE BEGIN 4 */
-void doInterruptThingy()
+int on = 0;
+void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
 {
-
+    if (GPIO_Pin == B1_Pin)
+    {
+        //do stuff
+    	if (on == 1)
+    	{
+    		HAL_GPIO_WritePin(GPIOG, G1_Pin, 0);
+    		on = 0;
+    	}
+    	else
+    	{
+    		HAL_GPIO_WritePin(GPIOG, G1_Pin, 1);
+    		on = 1;
+    	}
+    }
 }
-
 /* USER CODE END 4 */
 
 /**