We would need your budget really so if you can give us a price range that would help. I will give you some basic ideas for now which should help you pick your parts. Other people will probably disagree with what I say but that's the nature of choosing pc components, and ultimately you need to decide what you want from it.
Processor - Intel vs. AMD, this has always been the big battle, my opinion is that if your budget is constricted AMD is definitely the way to go, but if you can afford it Intel gives the better performance at the top end. If you let us know your budget I can make a better recommendation. I would recommend an I5 processor like the 6600 (the 6600k is the same processor but it's overclockable, something you might look at in the future) as it will handle almost everything you throw at it now and into the future. They are the standard for intel based gaming machines and won't struggle to handle pretty much any game you throw at it. An I7 would give slightly better performance but I don't think its worth the cost unless you're planning to do some video editing or other processor intensive work. I would also recommend a specialist cpu cooler such as the Hyper 212 evo or a liquid system, rather than the stock cooler since the stock ones will tend to let your processer get hotter which can cause issues with your system.
Motherboard - This is the part that holds it all together, and is essentially the nervous system of the computer. The reason I mention this after the CPU is that the motherboard socket must match the socket type of the CPU you choose. Other than that the only thing that changes is the number of expansion slots and optional extras such as sound cards. Motherboard is mostly personal preference as long as you get the socket right.
RAM - I would recommend about 8 or 16gb, 16gb is preferred for more multitasking but if you get 8 now it's very easy to add more if you want to in the future. Anything more at the moment would be overkill I think. I would also recommend DDR4 ram, though if you find one you like that has DDR3 then don't stress it too much - again this is dependent on the motherboard so check the RAM type that it supports, most modern board will support DDR4 though.
Graphics Card - Now we're at what makes a 'gaming pc' special, this, along with the processor, is where the cost shoots up. Again there's the Nvidia vs AMD battle. I have always been an Nvidia user, and have always found their cards to be very good so will recommend one of those. Others will report the same about an AMD card so it's up to you really. The Nvidia 10 series is very good, and you get a lot of 'bang for your buck' as it were, but if you give us a budget then we can make better recommendations. You mentioned battlefield 1, so here is a list of graphics cards and the fps they get just as a reference to start you off with some ideas - click here. Note that any Nvidia cards followed by an M (eg 960M) is a laptop graphics card that will not work in your computer.
Storage - This really depends on what you can afford, I would highly recommend buying an SSD if you can afford it, the difference in speed during Boot and game loading times is incredible. You will probably notice it less in games, but when your computer takes seconds to boot up you'll never want to go back to standard HDD's. Even if you just have a 128gb SSD for your operating system and a 1tb hard drive for your games you will still get the benefits of a fast OS.
- Wi-Fi card, you may need one of these if you don't have a cable connection, it will use a small PCI expansion slot on the motherboard so make sure you have one spare.
- Case, again personal preference as to which you buy, just make sure it has enough room for everything you want and make sure that you have enough fans to cool the system.
If you have any more questions just let me know.