Building a gaming pc on a budget

Hi guys, i dont know alot computers but i want to build my own gaming pc. I have a budget of 400-450. i do have some parts which i can use but i help with major things. 

Parts i have 

3gb ram ( )

Samsung cd drive

500gb solid state harddrive

Amd athlon ii x2 220 ( ) (might not use)

Parts i need help with

power supply, Motherboard, case, video card. ram(if i need to) and cpu.


Any help is appreciated.

P.S i do not know alot of specs and stuff so i gonna take your word for it. 


Do i need to get extra cooling system.

( )

or the 

( ). any ideas?