Hello Sakendar, as well as learning how to assemble the hardware you first need to look at the safety aspects of hardware assembly.
Such as adequate anti-static protection, you could blow out chips on your hardware through a static discharge and the new system you've just built may not even work.
You also need to learn about the different kinds of power connectors, it would be helpful to know about both old and new if you want to start building your own systems.
Then there is the different types of drives you can install e.g. sata drives, or wether you going to need AGP, PCI, PCI Express. The list goes on!
Once you've got the motherboard you want, you need to find out what kind of processor will work. Is it a 32bit\64bit, how much RAM will it take (how much do you need?!). What kind of RAM will it take? Does the motherboard have any onboard facilities i.e. sound, graphics, network adapter and are these sufficient for your needs?
Have you got enough power from your PSU to supply all your hardware?
Try and plan what you need the system for and what you want to do with it so as to ensure you've selected the right hardware and you don't waste any money or time.
It's good to see your prepared to make your own, but try and get as much research done as possible to avoid blowing anything up at great expense!
If you need any help or advice about how to install the hardware that you have selected to build your system, and to do it safely give me a shout and I can place a tutorial article on this site for you.
Also, if you need any advice about the hardware you've selected or what you might need for a good combination to what you've already selected there are plenty of people here to help.