How to add items to a list?

add a List action, then do a loop where you add elements to it

List
Repeat
    Ask for Input (Text)
    Add to Variable (List)
End Repeat

The output of a Repeat loop is already a list, so you can do this too:

Repeat 10
    Ask for Input (Text)
End Repeat
Set Variable (MyList) to (Repeat Results)