Guides
One question at a time, with the exact controls to use. For everything else, see the reference.
Get started in five minutes
Open the panel, pick the script, turn Mask values on, learn what the three tabs are for and where the help is.
Why is this field hidden?
Find the rule that hides an element, see what the data holds now, and try other values without touching the page.
Why can't I press Next?
List what may be stopping Next on the current step: empty required fields, firing Set Errors and validations, and custom components.
Why did this call fail, and what did it send?
Find a failed Apex call, read the reason, see exactly what the script sent, and compare it with a call that worked.
Test an Integration Procedure or Data Mapper
Read a debug run of a designer Preview on its Debug tab, get one without the designer, run it again with other input, send a test call of your own, or copy a call as Apex.
Compare two runs
See what changed in the data between two reads, what differs between two calls, and what changed in the script's definition.
Where did this value come from?
Find the call, the step and the Set Values element behind a value in the data, and see what each call changed.
What the panel keeps on this computer
See what is stored in the browser, what stays in memory, and how to clear each part.
Report a problem
Copy the panel's short report, save a masked debug bundle, check what is in it, and fill in the issue form.