https://speckyboy.com/photoshop-tutorials/
Before You Start
I usually use this texture but you can find more by searching "old texture" on google images.
https://myphotoshopbrushes.com/brushes/id/286/
^Click the grey download button
^DO NOT CLICK THE BLUE DOWNLOAD BUTTON THAT'S AN AD
^The above link is to download the paintbrush set
MAKE SURE TO EXTRACT THE ZIPPED FOLDER AFTER YOU DOWNLOADED IT IN ORDER TO FIND IT WHEN LOADING IT IN TO PHOTOSHOP
(I will show you how to load in the brushes later)
Step One:
Start by creating a new canvas based on whatever size you want. I would suggesst going 1920 by 1080 or even 1080 by 720.
Step Two:
Unlock the layer by clicking on the lock symbol on the layer.
Step Three:
Go to Filter Gallery