After much consideration, you took a big step and bought a 3D Printer! Congratulations!
Now what?
The first thing - breathe!
The second thing - STOP
The best advice I received from a friend of mine when I got my Ender 3 was to take my time assembling it up. Do it right the first time to avoid problems later.
Assembly
I will not recreate the wheel here. I strongly suggest that you use the following resources for assembly:
I watched Creality Ender 3 assembly and pro build tips video from Tomb of 3D Printer Horrors on YouTube several times. That channel quickly became my go-to reference for 3D Printing. I suggest watching this video before assembling your printer and referring to it often as you are going through your assembly.
Luke Hatfield's 3D Printer Help Guide Creatliy and Others
This written guide has every detail you will need for assembly. It is a long read but worth it if you get stuck or need some help. If you prefer written instructions, or just want to print out some guides for reference later, you should check it out.
Now that your Ender3 is assembled, you can start printing, right?
WRONG!
Do not just jump right into printing. You will have a bad experience. Check out our page on how to configure the printer before you start printing