Microsoft decision tree

I have an example case below :

Customer Id

Debt Level

Income Level

Employment Type

Credit Risk

1

High

High

Self-Employed

Bad

2

High

High

Salaried

Bad

3

High

Low

Salaried

Bad

4

Low

Low

Salaried

Good

5

Low

Low

Self-Emplyed

Bad

6

Low

High

Self-Employed

Good

7

Low

High

Salaried

Good

My question is how to make a tree from the case above I mean what method we should use to split the tree. (Mannually counting)

I hope anyone could help me by explaining i details.Because i want to make some analysis how microsoft decision tree works exactly.So Please explain me the process to build the tree completely with the method.

Thanks a lot.

Please clarify your question. I'm not sure what you are asking for- you want the equations used to determine a split?|||I'm so sorry because of confusing question. Yes what i mean is equations used to determine a split. Would you explain it detail for me? Because i 've made a thesis about microsoft decision tree analysis so i need to know how microsoft decision tree work exactly.
thank you so much|||

This article explains how the Microsoft Decision Tree algorithm works at a high level and also points to the relevant research papers that the implementation is based on: http://msdn2.microsoft.com/en-us/library/ms175312(SQL.90,d=ide).aspx