Pc wouldn't boot fixed it now it wont again

Hello,

i just got my new pc today this is my first time with a pc and not a laptop
so i plugged it in and it didn't work it said no signal on the monitor so i searched online where i was told to unplug everything hold the power button for a minute and then plug it all in which worked i then turned my computer off(before installing windows) and when i tried to start it again it had the same problem as it had to start with but now the trick does not work the fans are running and light too but i cant see inside i hope you can help

thanks and sorry for the bad english