Welcome Heidi!! Glad that you have found DC!! I hope you are going to have as much fun as we do!!
WTG for having decided to have a little more adventure with herbs and spices, you will be surprised how much they will enhance with your recipes!! Do not be shy, but some of the strong spices can overpower other ingredients, so until you get used to it just add by small pinches, then taste as you go rather than pouring spoonfuls into the food. Experiment, experiment, experiment, that is the key and the way to learn the way about cooking and how to use your spices!! Here are a few suggestions for you to start with, if not complete...I hope it will give you some idea.
You have a good start, garlic and onion would help just about any dish to be interesting and attractive, at least in my opinion.
Now, if you like pasta, or anything with Italian flavour, basil(though fresh leaves are much better if available, the dried flaked one in a bottle will also do) and oregano are must.
For Indian and middle eastern, african food, garam masala, coriander seed, cardamom, turmeric, cumin, ginger(also fresh one is recommended over the powders)
Nutmeg adds a nice touch to anything cooked with bechamel or creamy sauce.
Rosemary is a wonderful companion to roasted potatoes, as well as roasted meat, especially pork.
Bay Leaves are also indispensable for anything that will be simmered in liquid for some time, like sauces, risotto, stew etc. Gives your recipe a lovely twist. (don't forget to discard the leaf before you dine...)
Cinnamon is also wonderful for desserts, or to add some surprising twist to other dishes.