Here are some links on conditional value lists that may help:
Forum Tutorial: Custom Value List?
Knowledgebase article: http://help.filemaker.com/app/answers/detail/a_id/5833/kw/conditional%20value%20list
If you have any additional questions on conditional value lists after reading these links and/or examining the demo file, feel free to post them.
Thank you very much :) .I'm wondering where to put this conditional value list whether in the original field or the result field?
You need to explain what you mean by "original" and "result" in the context of your layout's design.
Using the wording of your original post, the "other field" would be set up as a conditional value list. The values shown in the list are normally drawn from a separate table of values, but it's not impossible to set it up to draw values from the same table if you want user input to automatically add new values to the list. That approach would require a self join relationship.
Let me know exactly what you have in mind and I or another forum participant can then help you fill in the details.