I'm assuming you wanna build a PC that you can then leave to run/game without worries with at most occasional dust cleaning, and that you won't be tinkering with it a lot (like overclocking etc).
Generally you have the below computer parts where you need to consider.
-CPU: 4 cores recommended, and gaming isn't CPU intensive so 4 cores maximum. Therefore Intel Core i5/4460. Done.
-RAM: Depends. If you're short on money, 4GBx2 or 8GBx1 capacity DDR3 is fine. 8GBx2 if you like to run 100 chrome/FF tabs, play music and game at the same time. Don't worry about the RAM kits or speeds, just get the cheapest value RAM, but if you're getting two make sure they're of the same speed/latency.
-Motherboard: Any B85 ATX board, just go for the cheapest one. Some are B85M, that just means they're of the smaller mATX size which is fine; they're cheaper too. The price variation is mostly brand reputation and some features here and there; if you have to ask, you don't need them.
-SSD/HDD: Just go for cheapest HDD at whichever capacity you want. Currently it's Toshiba. If you got a bit of extra cash, get the cheapest SATA SSD (~240GB recommended) to use as the main program/OS drive, and dump the rest of your games, music, videos etc to the HDD. HDDs are all at roughly the same level performance wise, and current SSD performance for the average user is blazing fast no matter the brand or model.
-GPU: Things can look complicated here with the 2 brands' range of models and all the vendors in between, plus your choice depends heavily on your monitor's resolution and the games you play, not to mention the minimum game graphics settings you want to play at. Vendor differences to take note mostly boil down to the convenience of the respective local distributor's location, the outputs of each card offered, power consumption, and the quality and noise of the cooler (if power consumption is high), but generally going for the cheapest version of whichever model you decide to buy won't be potentially disastrous. This along with the CPU/mobo & monitor is likely to be the most expensive component of your computer.
-Case: Depends on a lot of factors of course. You can pick a really cheap crap $30 mATX case, but they are usually a nightmare to try and install your parts in, have **** airflow so your computer runs hotter, are messy and difficult to clean, and often rust FAST. That doesn't mean you have to splash out of course; there's a minimum acceptable standard beyond which there's no need to spend any more. Personally I advocate spending ~$100 on a decently built and spacious case with easily removable fan filters for ease of cleaning. There are many models and brands to choose from (Fractal Design, Silverstone, Coolermaster Silencio series, Corsair), so ask around. Ensure your case can fit your mobo's standard size.
PS: Looks and fancy LEDs are pointless. The thing will sit below the table out of sight forever.
-PSU: Stories abound of no-brand $30 PSUs exploding and taking entire systems with them. Thankfully prices are low for all the reputable brands' basic models so you don't have to splash out for safety. Your PSU choice will depend mostly on your GPU's power consumption (which determines your wattage), and whether you want neat cable routing in your case (in which case go for modular PSUs which have removable cables). You can safely go for any 430-550W model for any current-generation AMD/NVidia GPUs below the GTX1080. Seasonic, Silverstone, Superflower, FSP are all fine.
CPU cooler: Only if you're really particular about CPU fan noise, or if you're going for K Intel CPUs. For the former, just get a $20+ Deepcool Gammaxx 200, it's the cheapest usable CPU cooler around.
