Moved the thread to correct forum - Tools Development.
It is recommended to have enough tools training before you start working on LN Tools. A basic training is required to go ahead and start developing your own scripts, reports etc. If you get to know the basics, you will figure out the rest easily.
Coming back to the question -
You can search the questions on the board and you might find the answers -
Here's a thread for sum.
Also, you can get the Developers Guide from Infor Xtreme and see if it helps.