You have multiple avenues to create the options for your Datalist fields. Most, follow how other ExpressionEngine option based fields operate so it should be straightforward.
Value/Label pairs can be used to make content selection friendlier to content authors. For example, if you need to store a value of 1, you could use a label of One.
Each item in the textarea will be included in a datailst drop down menu in the publish form.
Select the Channel Field you want to use options from.