Can somebody show me an example of the feature "Mold" use?

If by mold you mean "mold tools" then here is an example. The model I show is very simple. Molds can get much more complex, but the steps remain pretty much the same. So... start with simple. Even simple take many steps. I have attached the model file in roll-up, so you can step through to see how it works.
Hope this helps. PS SW also has a tutorial on their help page as well.
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Step 1:
1: Part. Cup with hole in bottom
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Step 2:
2: Mold tools
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Step 3:
3: Parting line
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Step 4:
4: Select face
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Step 5:
5: See results
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Step 6:
6: Parting line established
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Step 7:
7: Select Shutoff
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Step 8:
8: Shutoff complete
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Step 9:
9: Shutoff completed
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Step 10:
10: Select parting surface
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Step 11:
11: Establish parting surface
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Step 12:
12: Parting surface
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Step 13:
13: Select tooling split
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Step 14:
14: Select plane
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Step 15:
15: Create sketch
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Step 16:
16: Features created
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Step 17:
17: Mold created
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Step 18:
18: Mold in section.
ENJOY...