I applied for a credit card at bestbuy last april and think im in trouble?

ok so i applied for a credit card at bestbuy and i didnt really think too much about it and didnt really know wat i was doing, but i have no crredit history and when i applied it denied me and gave me a letter in the mail saying so...just a week ago i tried buying a ring for my fiance and they said i cannot buy it there because on my credit history,,the bestbuy creditcard thing shows up and for some reason they wouldnt let me buy it, and i just dont want to be screwed cuz i was stupid and applied for that last year...how can i fix this,, cuz i would really like to buy her the perfect ring and im in the airforce right now,