First type the list without taking care of the numbering just make a return after each items of the list like below :
Type the items of the ordered list like that :
item 1
item 2
item 3
Select all the items and clic on the List= button : You will get that : Add the value right after the "List=" you want the ordered list started with. So 1 will start with 1 then 2, 3, 4 and 61 will start at 61 then 62, 63 , 64. You can also use a letter instead of a value. Using A the ordered list will start with A then B, C, D etc... (Just test to see how it looks with a preview before posting). Add the [*] tag in front of each line by inserting the cursor in front of the items then press the [*] button. This will indicate to the board to add an ordered value or item at this place. Submit the post (or make a preview) and you will see that :
Here a list of ordered items :
- item 1
- item 2
- item 3