In your example NumberOfItemsToTake would be an integer of value 200. Your NumberOfItemsToSkip can be modified by a counter in a loop. Set the counter to 0 first and assign NumberOfItemsToSkip = counter * NumberOfItemsToTake. So on the first loop it skips 0, just gets the first 200, then skips 1 * 200, 2 * 200 and so on and so forth.
As a newbie you should practice designing your solution yourself. Here are a couple more tips:
Find out how many output files you need by dividing YourDataTable.Rows.Count by NumberOfItemsToTake (200) - find out how to round up numbers in the forum
Use a While or Do While Loop and in the condition compare the number of needed output files with a counter (integer variable)
Follow my last response to split the DataTable and write the “current chunk” in an Excel file within the loop, so you get one file for each iteration
Of course at the end of the loop you need to set the counter = counter + 1