Hi Rose,
I'm fairly new to SL as well and I did the same thing as you and bought several articles from the marketplace at one time. I didn't receive any of these items in my inventory, even though my purchase history showed they were delivered.
Since then, I've discovered that the best way to use the Marketplace is to NOT order more than one thing at a time. Do each one individually, wait for it to be delivered - and also, most importantly, you should be logged on to the game when you are ordering, and not be status as "busy". There's some glitch, or bug with the Marketplace which causes this nondelivery to happen with multiple items in the shopping cart.
Occaisionally, I still have a problem of nondelivery using the Marketplace, but not often. If you do have an issue, the best way as stated is to contact the merchant by making a notecard from your notecards folder (right click on it to make a new notecard), find the merchant's name, copy and paste your purchase from your account history area on to the notecard and poilitely explain the problem, then share the notecard with the merchant. 9 out of 10 times you will receive your item, doing this. Sometimes, you can contact merchants via IM as well, but most prefer notecards.
Hope this helped!