Thanks for the photo it helps a lot and tells me the soil is dry in this area from the tree. The Japanese anemone will do great and give fall color. Daffodils, snowdrops and hellebores can give early spring color. Peonies and euphorbias are two perennials that can offer late spring summer and astilbe is a summer perennial. To give some evergreen structure there are low growing yews that can handle the shade, or you can place a large container in the bed as a focal point and grow hosta or nandina in the container. A dwarf Japanese maple might also fit into the space and would look great in a more rustic container.  Ajuga or crane's bill geranium are two good evergreen groundcovers for the shade.   Take your time, enjoy the design process and improve the soil when you plant and add a mulch to conserve moisture. It will be lovely. Keep growing, Marianne Binetti