Open your Yahoo Mail account and select the Contacts icon. (This may be on the right side menu, or on the top left menu, depending on your version of Yahoo Mail.)
(Right Side Menu)
(Top Left Menu)
Click Actions, and select Export from the drop-down menu.
From the pop-up box, select the Yahoo CSV Format and click Export Now. The file will be saved to your downloads folder.
Now, it's over to Traktivity. Visit https://app.traktivity.com/contacts and click Import Contacts. Then, click the box that says Yahoo Contacts.
Select the file you just downloaded from Yahoo, and upload it to Traktivity.