Hello,
If you’d like control of each transport command, you’ll need to use an aux switch or MIDI controller. If you’d like to control everything from the H90, you can use the 1-button looper. All the information about the looper can be found here: https://cdn.eventideaudio.com/manuals/h90/1.3.0/content/algorithms/looper.html
Try loading the Looper into Preset A. Then press the Perform button, and press the A LED button until you see the 1-button looper functions. Read the instructions in the user manual above for details about the 1-button looper. Use the max length parameter to determine how long the loop is.
Let me know if that clears things up for you.