To add a checklist you need to have Level 5 permissions. To add a card to a checklist that already exists you need Level 8 permissions.
https://www.tcdb.com/Permissions.cfm
If you use the Card Identification forum there is a spot you can upload a scan of the front and back of the card. That will then let the membership help identify where the card should go. Then you can entire an Inaccuracies Report. If the set already exists from the sets checklist page click the link that looks like this
See any inaccuracies?
Click here to let us know
If the entire set is missing research and find as much checklist info you can and go to the sport/year of your set. On the top right of where all the years are listed click on the green Missing Set button and enter as much info as you can...including your checklist or a link to one.