Hi Kristin! *wave* Glad you've been able to get into the swing of digi-scrapping!
As for credit... yes, it's necessary, when at all possible, to give each element's creator credit when you post. Perhaps you can at least give a website if not an individual's name? If you dled most of them here, you can look back in the Elements section for their name and/or ask us when we comment on your work to let you know who made what.
In the future... make sure to store that information in the file name!

I usually rename the elements I dl into what it is, as simplified as possible, an underscore, and then the person's name, i.e. bigsunflowertag_leeandras.png. I know some more organized women also have Excel spreadsheets to store all that information for future reference.
HTH!