Hi, nice to meet you! Sure, I can give you a hand. Building a computer is actually surprisingly easy, thought it does take a bit of know-how in terms of choosing your parts. I have some helpful resources that I could give you to get you started, and if you need any in-depth help or would like my opinion on anything, feel free to ask.
Firstly for websites, there are many that are good for ordering parts. Assuming that you live in the US, some sites that I would recommend would be Newegg and Tiger Direct, though there are many others that are just as good. Essentially, you'll want to order parts from whichever sites will give you the best deal, or are most convenient.
As for being able to run games on max settings, what you're mostly going to need is a good GPU. The GPU is your graphics card, and for most games it will be doing the bulk of the processing and rendering. However, that doesn't mean that you should skimp out on your CPU or RAM, but they're not quite as important for gaming. A really good computer that will be able to max out games could cost as much as $1000 US, or more if you want it to be even better. However, it's not entirely necessary to spend that much.
Now I'd like to provide you with some useful tools that can get you started. Firstly, there is a really useful site called PC Part Picker that will show you all of the components necessary for your computer, what their prices are at which sites, and all of that useful information. This is a great way to lay out your build and make sure that you have everything that you need. Additionally, for actually deciding which parts you want to buy, there is this really handy guide called Falcon Guide. Yes, it's made by a guy from 4chan but don't let that deter you, it's an incredibly helpful guide and a great starting point. It will show you recommended items for price ranges ranging from $200 to $2000. You shouldn't necessarily treat this guide as the bible, but it's incredibly helpful for a first time build.
Now that I've got that out of the way, if you'd like more assistance it'd be great if you could give me some more specific details on what you're looking for. Price range, what you want to do with the PC, what you want to play, ect.