Download Unity 2017.4.15f1 - https://unity3d.com/get-unity/download/archive (Make sure you click on "2017.x", then find "2017.4.15")
VRChat SDK - http://vrchat.com/download/sdk
Home Kit - https://assets.vrchat.com/kits/VRChat_HomeKit_v1.unitypackage
Home Kit is a Unity Package with the assets you’ll need to customize and upload your own home. The tutorial is aimed at beginners, so it’s a perfect starting point for building your first VRChat world.
Please note: The VRChat Home hasn't been updated for Unity 2017.4 just yet, but it should still work fine when imported into your project. If you have issues with newer versions of Unity, let us know!
We’ll create a Unity Project, import the VRChat SDK and Home Kit packages, and customize your home with furniture, materials, and lighting. After that, we’ll upload your world and set it as your default Home in VRChat.
You should feel comfortable navigating around in Unity and have a basic understanding of the interface.
To use the VRChat Home Kit, you need a VRChat account, not a Steam account. Steam accounts can never gain the ability to upload content.
Register Here: https://vrchat.com/register
If you're a new user and cannot upload content yet, you can test locally. Once you've participated in the VRChat Community and have received the privilege of uploading content, you can upload your version of the Home.
Keep in mind that you should always follow the Community Guidelines and the VRChat Terms of Service.