Designing
Step 1 - Take a list and put the items you want
Step 2 - put a label above that list
Step 3 - Set list viewer visible to false
Blocks
Step 1 - When label click set list viewer visible true.
Step 2 - When list viewer item click take a variable set that variable to item and set lsit viewer visible false.
If you want an example you may see the translators app by alebrt.
Thanks
Namit