The Pick List field allow you to create a set of values you can then select from in a record. The Pick List offers a convenient way to limit the value of a record field to only a certain set of values.
Note: The pick list doesn't offer any kind of in-field editing (meaning you can't change the pick list option while editing a field. If you're looking for something like that, I recommend using the Reference Field as a pick list. It works very effectively and provides a lot more options.
Pick List Editor - There is one main thing you have to do to properly setup a pick list: Set up the values. If you tap on the "Pick List Editor" button, you'll be brought to a list management screen you can use to add, remove and rearrange your pick list. If you need help with this, see the List Manager Tutorial.
You can rearrange and edit your Pick List names without messing up pre-existing values. Of course, if you remove a pick list item, any record that uses that item will no longer have a value set.
Default Value - Use this to set one of your Pick List values as a default. The default value will only be inserted for new records.
Selecting a value in a pick list is simple. Tap on the field to open the pick list selector. You can then scroll and/or tap on an item to select it.
The toolbar will also contain a trash icon you can use to clear the pick list of a value.