Easy stuff man. Use PC parts picker and the compatibility filter to find you a case, a Mobo, a CPU, a cooler, some RAM, a power supply, a hard drive, a graphics card, monitor, keyboard, mouse, and a windows 10 usb.
Open up the case and the power supply, then install the power supply into the case with a couple of screws. They should come with your case. Next install the mobo by aligning the ports panel with the hole for the ports, then affix it to the case with the screws. Next install the CPU onto the mobo per the instructions, then install the cooler on top of that. Again, just follow the instructions. Then install your RAM per the mobo's instructions. Next open up two expansion slots on the back of the case and install your graphics card by plugging it into the mobo. Then put the hard drive into a bay and fasten it with screws. Next start running cables. Get the cables for your case's LEDs, power buttons, and fans plugged in per the mobo instructions. They should all be labeled and the instructions will tell you where the go. Plug in the two power cables on the mobo, then get add cables to your power supply to give juice to your hard drive and your graphics card. This is fool proof because the ports that fit are the right ones. Next, find a sata cable and plug one end into the port on the mobo and the port on the hard drive.
After that, put the case together, plug the windows 10 usb stick into one of the ports, plug in the power supply, plug in the keyboard and mouse, plug in the monitor and attach it to one of the ports on your video card, then hit the power button. Windows 10 will guide you through the install process.
Ez pz.