This tutorial will show you how to wire and attach the 310mm heated bed.
And you can learn about the power expansion module for the big size heated bed.
You need soldering iron and wire crimper.

You can see full instructions in the link below.
https://www.instructables.com/id/Buil...

0:00 Intro
0:07 Step 1. Parts List
2:28 Step 2. Making 4pin Power Connector
5:31 Step 3. Attaching the Thermistor
6:28 Step 4. Preparing Bolts and Nuts
7:38 Step 5. Attaching Heated Bed Brackets
9:11 Step 6. Installing the Heated Bed
10:47 Step 7. Wiring Power Expansion Module
13:06 Step 8. Attaching the Power Expansion Module
14:58 Step 9. Attaching Heated Bed Sticker