This tutorial will show you how to create a drop down list from data source cells.
Step 1: Have cells with some values, it will be your source for the list.
Step 2: Point at the cell where the list will be.
Step 3: Click on Data then click on Data Validation.
Step 4: On Settings tab select List from the Allow section.
Step 5: Click on Source button select cells then press Enter then click OK.