NOTE: IF are ever going to touch anything inside the case be sure to rid yourself of static electricity(you do this by grounding youself by touching the outer part of the case)
The first thing you need to do is make sure that everything is compatible and has enough power.
The second is to install CPU to motherboard/Heat sink and fan/RAM.
The third thing is to install assembled motherboard into case.
The Forth step is to install the power supply(the cords can get in the way so you can delay this)
The fifth step is to install the disk drives/ Hard drives/ and other drives(please god tell me you don't have a floppy)connect IDE's and SATA's along with power at this time to drives and motherboard.
NOTE: the case is going to get more crowded so keep in mind placing hardware for easiest access.
The sixth step is to install all PCI cards(Vid Card/TV tuner/Wireless cards etc.)
At this Time you should have all hard ware installed.
Now it's time to power up. make sure you have the operating system disk in the disk drive(do so during boot up) In the opening check list that the CPU does you need to select BOOT from CD/DVD drive(with the OS disk inside)
If your comp does not power up make sure that all power connections are in fact connected properly. If you still have problems let me know.
NOTE:If you are using an old hard drive that was formatted with a different processor and/or motherboard you need to reformat the hard drive with the Operating System(This will erase everything on your hard drive, but it will work smoothly)
The process is basically put things where they fit and if all else fails...consult YouTube.
