You have a couple of main options with populating the listbox/dropdown options.
Firstly, you can select "External Source" and then link your file that contains your relevant values.
Secondly, you can copy and paste these in to the interface tool after selecting "Manually set values" (Tip: if your Name & Value are equal then you can just list the names rather than Name:Value).
It is not designed, so that you can populate the dropdown with all the values in one of the columns of your dataset.
That being said, there is possible workarounds
Let's say that you have a column called name and it contains 25 rows consisting of 5 different possible values repeated, I can run this through a summarize tool Group: Name. If you wanted to use this for an interface tool in the same workflow then put this into a crosstab tool so then the unique values of that field are field names and will appear in the dropdown/listbox. The issue with this is the metadata not flowing through the cross-tab properly to populate the listbox dynamically (also issues with punctuation/spaces etc, which would require dynamic rename)... so the better option is chained apps.
Your summarise tool from the above example can be run through a formula tool to create NAME & VALUE columns then written out to a templist.yxdb file, this can then be an external source on dropdown for the next app. So, the first app will just select which field you want to use to populate the dropdown and on clicking finish, it will perform the necessary operations and then write that out. In the interface designer on that app, you can choose to run anoth app on completion, where you would choose the second app so that it runs automatically.
All that being said, you can always just make sure that you have a NAME & VALUE field in your original data and select your original dataset as the External Source for the interface tool.