First lesson in gardening - PATIENCE!
It's a very frustrating time in the garden because, as everyone has said, nothing is really happening at this time of year, not that you can see. All you can do is wait and see. However,if you go out and look closely you will probably see lots of stuff just beginning to shoot.
However, there are things you will be able to plant later in the year that will be flowering this time next year. You have plenty of time to do some research, and a few suggestions of the top of my head are:
Bulbs - crocuses, muscari, iris reticulata, which would all be popping up now, daffodils and tulips which will be next.
Shrubs - witch hazel is a lovely shrub for winter, also some viburnums will flower now. Forsythia will be out soon and Daphne (which has a wonderful scent) different rhododendrons flower at different times too. Seeing what you have already will guide you towards what new things will grow well.
I'm sure others will have more ideas,
You won't get it all right straight away, it's a constant learning process, this is a great forum and there's loads of good stuff on YouTube too.