Please show me how to work out 9.986 divided by 3060.408?

It's called long division. For an introduction, see
https://www.mathsisfun.com/long_division.html.
http://www.calculatorsoup.com/calculators/math/longdivision.php

If you are uncomfortable working with the decimals, just multiply top and bottom by 1,000.
9.986/3060.408 = 9986/3060408 = 0.003........and so on.

you can simply use the bus method for (short) division

Both numbers have three decimals
Multiply both by 1000 and then divide:
= 3060408 / 9986