Before you can start using your new Advanced Select List based custom field, you have to create it - add it to the custom fields list.
To create new custom field:
Click the JIRA Administration icon and select Issues.
Choose the Custom Fields link in the Issues section.
The Custom fields form appears. Here you have all the existing custom fields listed with the possibility of editing and configuration.
Click the Add Custom Field button at the top of the page.
Here you got the Select a Field Type dialog, where you will select desired type of the custom field - Advanced Select List. Click link for All existing types in the menu on your left.
Select a Field Type dialog
Select Advanced Select List custom field and click Next.
At the Configure Advanced Select List Field dialog enter the Name and Description of the field. The Name of the field will be visible right at issue page together with Description which guides the users to select appropriate option value.
Initial custom field configuration
Now you can enter the range of values, that you will be able to administer later as well. Enter the value into the Option field and click Add button for each option. By dragging the option you can modify the order of the values.
Click the Create button at the bottom of the dialog.
Note the re-index recommendation at the right top off the page. While you're adding the new field into the database, it is strongly recommended to perform reindexing your database to keep its integrity and performance.
Expand: Reindex recommendation
Now you have been redirected to the Associate filed to screens form, where you can see the list of the screens avalable for associating with your custom Advanced Select List. You can provide the associations also via Administration/Issues/Screens menu. Select the checkboxes for all the screens you have chosen. Unless you change the order of the screen fields, the added custom field will be shown as the last one on every screen. Click the Update button to save your changes into the database.
Associate filed to screens form
You're back at the Custom fields list. Your newly created field is now available in the list and prepared for use.