Simple Redstone Door can be operated from both sides by using redstone dust under it. Just step on the stone pressure plate to open up the gate.
This guide will let you know how to make a Simple Redstone Door in the Minecraft game.
The first thing you will need to do is to place three pistons on the ground and three more by leaving a gap of four blocks on the right.
The next you need to do is to place a gray concrete block on the outer side of the middle pistons and place a redstone torch at the bottom of this block. Use redstone dust at the top of the block to push the pistons. Follow the same on both layers of pistons.
Place black concrete blocks in between the pistons and dig 3 blocks deep ground in front from one torch to the other as shown in the image below.
Add a layer of dirt in the center part of the dug ground and remove the grass block under the torch to place another redstone torch there. Place one more redstone on the side and connect them by using redstone dust.
Follow the same on the other side of the dug ground and then use redstone dust on the dirt blocks in the middle.
The next thing you will need to do is to fill the gap by placing the white concrete blocks and then add a stone pressure plate in front of the door.
Step on the gate to open it up and then go back to close the door.
Now you have to connect the other side of the door. Dig the ground under it and use redstone dust on the floor.
Cover the ground again using white concrete blocks and place stone pressure plates on the other side of the door. Now you can operate this door from both sides.
And finally you have to cover the redstone by using black concrete blocks on all the sides and dark oak slabs at the top as shown in the image below.