First....make sure you choose the right input on the monitor!
If you're using an HDMI cable, make sure the input source on the monitor is set to HDMI, etc.
As far as I can see, that CPU has no integrated graphics so let's focus on the GT610. Please have that installed in the bottom (closest to bottom edge) light blue slot on the motherboard (PCIe 2.0) and use either DVI or HDMI cable to connect to the monitor you wish to use with the system and select that input on the monitor and start the PC.
If no image, try the other PCI-e slot and repeat (no need to change input on monitor if using same cable). If you have both a DVI cable and HDMI cable, try each cable, combined with the corresponding input selection on the monitor.