You need to connect your PC via USB connection to FFCP, then:
1. run Simplify3D
2. Click on Tools and select Machine Control Panel
3. Normally Simplify3D will automatically connect to FFCP, if not then click on the Connect button
4. Click on the tab Communication
5. In the dialog box next to the Send button (bottom of the page) type the g-codes
6. Click the Send button
You should see the BLTouch pin head go up and down when you send the g-code