You can add columns to your List by hitting this button top right

Then selecting Manage Columns 

From here you can add, delete and edit existing Columns. You can also choose whether you see your card image etc. 

Press the + To create a new Column. 

You can choose from variety of Column Types:

Field - you can choose a field from your Cards, for more on Fields, click here

Rich Text - text just for your list (not on the Card itself)

Currency - a dollar value (you can edit the currency)

Number - a numerical value

Date - a date selector

True / False - a checkbox

Filedrop - if you have created a file request from this Card, the unique filedrop link will automatically populate here.

Email - the default email address on the linked Card

Phone - the default phone number on the linked Card

Hit Save & Close when done.