The first thing you should do is research. Browse some build guides on YouTube from Linus Tech Tips, Bitwit, Jayztwocents, Austin Evens, etc. There are plenty of build guides to help you learn how to build them and what parts to consider for your budget.
The second thing is one that you already outlined: Budget and needs. You have the budget at $1000 and you already know what you're going to be using your PC for.
Third, build a parts list. You can use PCPartpicker.com to select parts and check for compatibility and prices. This tool is extremely helpful.
Lastly, build the thing. This is where the build guides will help. Take your time and triple check everything you do.
If I were to recommend a starting point then I would suggest an AMD Ryzen build or an Intel Core i7/i5 build. You should consider either an AMD Ryzen 7 1700, Ryzen 5 1600, an Intel i7 7700k, or an i5 7600k and pair it with a decent motherboard. For for your GPU, I would suggest a GTX 1070.
Your budget will be your guide and you will find yourself going over it lol. Try to tweak your build to get as close to your budget as possible. If you need help then this forum is full of helpful tips and tricks and troubleshooting solutions.