Question about Dell U2719D

I assume you mean VGA (computer) to HDMI (monitor).
As this monitor has no analogue interfaces, you need an active adapter:
Delock VGA to (HDMI, 25cm)
The USB port is essential, as it supplies the adapter with power.
But don't expect miracles, VGA is not made for high resolutions and the adapter supports FHD (1920*1080) at most.