Assembling a computer is very easy provided need to be bit careful while giving power connections and fixing peripherals to the motherboard. I will explain in detail how to assemble a desktop computer.
You can choose INTEL, GIGABYTE, ASUS, MSI and many more depending on motherboard features and obviously your money limit). I personally recommend INTEL
Processors depends on the speed (Example: 2.8Ghz (Giga Hertz), 3 Ghz, etc). You have INTEL and AMD processors available in the market. I recommend if you are looking only for gaming purpose, you can choose AMD. Please note that when purchasing processor, whether INTEL or AMD make sure with the vendor that the processor supports the motherboard which you are planning to purchase.
(3) RAM (RANDOM ACCESS MEMORY)
RAM is available in different types like SDRAM, DDR1, DDR2, DDR3. Some motherboards support only DDR1 and some DDR2 or DDR3. So make sure that the RAM you purchase supports the motherboard.
(4) CDROM /DVD-RW /COMBO DRIVE
Many brands are available such as LG, SAMSUNG, LITEON etc.
(5) HDD (HARD DISK DRIVE)
Many brands are available such as SEAGATE, SAMSUNG, WESTERN DIGITAL etc. There are two types of HDD available. They are IDE HDD and SATA HDD which can be fixed inside cabinet.
(6) ATX CABINET
Cabinet is a metal or metal coated box where you fix motherboard and all other peripherals related to computer.
(7) SMPS (SWITCH MODE POWER SUPPLY)
SMPS is the power supply where you connect the computer from main power supply using power chord.
This is an output device available as two types. One is CRT and the other is LCD. CRT monitor is heavy when compared to LCD monitor.
Note: Always remember to check with vendor for compatibility and support of any hardware peripherals with motherboard you purchase.