If you are entering multiple cards of one player, search for his name and click on it. Then follow the links to where you can update your collection. I just entered all of the players I collect over the last two weeks, 17,000+ cards. If it is a partial set or full set, then search fo the set. It will then allow you to update your collection from that set.
It only took a couple of hours to get used to some of the nuances of the site but by far, this is the best site I have ever come accross for collecting.
Hope this helps.
Bruno
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Check my Profile page to see my 2023 Goals and my Lists of sets near completion (5 cards or less) or sets getting close (less than 100 cards missing and 75% complete).
https://www.tcdb.com/Forum.cfm/Page/B/ID/0/?MODE=VIEW&ThreadID=25745&C=0