Because the power strip you get might have a slightly different design, I suggest you start at the official Tasmota wiki. If you’ve never worked with FTDI programmers and/or Arduino you may need to invest some time getting familiar with the tools required. The link in my previous post has some basic steps with pictures for my specific unit. It’s not overly complicated, but it may take several hours of dedicated focus if you haven’t worked with microcontrollers before. I’ll do my best to assist you if you take a stab at it and have issues.
That unit from Digital Loggers has a single input that controls three switch outlets. Two of those outlets are normally off, and the other one is normally on. When you apply +5v to the trigger it reverses the state of all three outlets simultaneously, disabling the outlet(s) that were on and enabling the outlet(s) that were off. Notice there is only one trigger circuit on the unit… it’s not designed to switch outlets independently.