CAUTION - You need to be signed in to your google account and click the Download button then in the File menu select Make a Copy to have a version of the template that you can edit. The inserted documents above the Download buttons are just previews
The Character Summary Template shown on the left doesn't seem all that helpful when empty, so below is an example about how you can fill it out.
Keep in mind that you fill out the details mainly for yourself, so don't be afraid of using descriptions that'd make sense only for you. The goal is to collect the essential informations about characters and to have a brief flavor text that is just long enough so you can use to expand upon, but not long enough to get lost in fine details.
Seeing all these in one row with a reference picture can increase your productivity and kick your brain in high gear when you quickly need to remember details, plus the filters on the top making it easy to find someone in the "crowd" based on name, post/occupation or age.
Visual references: Use the internet, search images based on key words that you feel would best describe the character in your head.
Don't limit yourself about picking a picture, based on copyright or other concerns because these pictures will be only used as a visual reference in your description.
You'll use them to solidify the character in your head and inspire the summary description (flavor text) about the character.
Said descriptions coming from using your imagination when looking at the pictures, and with that these references serving the dual purpose of forming the character and also help to ground them.
( With that being said I've got no clue who the people are on these images but can't very well blur them out while trying to explain the method of filling out the Character Summary sheet. )