Simple Google Drive Script

I need a basic script to add to a google spreadsheet. - One column of cells will either have a check mark character or no character. Data validation will provide a drop down to select check mark. (This is a workaround because checkboxes are not available in google spreadsheets. - When the value of the field is edited it will change the value of a notes section of another cell in the same row. -check mark character selected in L9 change value of I9 notes to: reminder_sent -if nothing is selected (default) in L9 it will erase contents of I9 notes.