STEP 1: Go to Settings > Web Content > Files
STEP 2: At the bottom of the page, select the 'Choose File' button
STEP 3: Search your computer for the correct file and select 'Open'
STEP 4: Select the 'Submit' button
NOTE: check the 'Overwrite if file exists' to replace a file with the EXACT same file name.
STEP 5: Copy the URL of the file
STEP 6: Got to Web Content > Site Map
STEP 6: Select the Title of the Menu or Sub Menu item
Step 7: paste the URL in the filed below