I've looked at the builds in this subreddit and I want to build a PC. What's next?

Hi everyone,

I'm extremely inexperienced when it comes to computers, but I want to build a gaming PC. I think the 60 FPS Ultra Build is in my budget and will give me everything I need. I see that I can order the parts online, but what's next? My questions are:

Do I need to order additional parts/software like power cords, or buy Windows 10?

Is physically assembling the PC self-explanatory or will I need help?

I'm sure there are plenty of things I'm not even aware of. What other information do I need to know?