Need help with my first Pc pls

I recently built my first Pc but Idk why it doesn't work:

When i turn it on the psu light is normal and the cpu cooler is working but my screen say he doesn't feel anything from the hdmi port. The cable management looks alright.

The problem isn't from the screen or the HDMI cable.

Why do you think I don't have anything on the screen ?

motherboard : ASRock B550M HDV

Processor : AMD Ryzen 5 4600G

no graphic card but the radeon graphic on the processor.

a 1TB SSD (NVMe) and 8GB RAM