How do I log a workout?

Follow the session your coach wrote, or log something freestyle if you are training on your own.

Open the Train tab
If your coach has assigned you a session for today, it is waiting there.
Work through the sets
Each set shows the target: weight, reps, and whatever else your coach prescribed, including RPE, RIR, tempo and their own cue.
Log each set as you finish it
Enter what you actually did. It does not have to match the target, and the gap between the two is exactly what your coach wants to see.
If there is nothing assigned, train freestyle
You can start an empty session and add exercises as you go. It is logged the same way and counts the same.

Worth knowing

Rest timers run between sets and can be started from the wrist as well as the phone.
Personal records are detected as you log them, so you do not have to remember what your old best was.