How to change ddr3 & ddr4 ram or Add ram

How to Install and Remove DDR5 RAM in a PC can i put ddr3 in ddr4 slot GIGABYTE GA-J1800M-D3P Motherboard with Built In DDR3 Celeron Processor GIGABYTE B760M H DDR4 mATX Motherboard Supported CPU: 14th12th13th Gen cannon cove slot Every DDR generation is different from the others DDR4 is not backward-compatible with DDR3 so a DDR4 DIMM will not fit on a DDR3 DIMM slot

can you put ddr3 in a ddr4 slot I install the ddr4 ram it had before and it powers on, fans start, ok lights up, monitor turns on but has no visual and turns down