Finally got into Altered!! Got some questions tho

Ive got into Altered!! I've bought the Ordis starter pack and also 6 Booster packs!! (No good pulls, or at least is what I think). I was wondering, how and where can I buy non-scanned single cards that I'll prolly need?? The last saturday I had my first mini tournament, 5€ entrance and 1 booster pack and one promo pack assegurated for each person. 2 promo packs for the winner

Also I dont know how trading cards online will work, cause at my lgs proxies aren't available, we need the ownership AND the original card. So how can I get single cards physically and the digital ownership? When I get the explanation on how to do It, Ill put my username if somebodys willing to do some trades.

Thanks to all this amazing community for all the upvotes and help I've got!!