Here's an excerpt from a Berkeley Hort article that describes planting and caring for the Cornus florida Dogwood.

In planting your dogwood, it is important that you choose your site carefully. In their natural habitat they are understory trees, receiving dappled sunlight through surrounding branches. In the East Bay a sunny spot for most of the day is good but protection in the summer from hot afternoon sun is crucial. In hotter climates provide more filtered shade from noon on. Dig a planting hole double the size of your pot and amend with slightly acid fir mulch. Avoid a wet site and in our native clay soils I recommend planting high in a slight mound so that as the soil settles the crown of the tree rests slightly above grade. Mulch with organic matter up to 4" from the crown of the tree and water in well. Dogwoods should be watered deeply at least every 10 days and during dry spells at least once a week. Fertilize in the spring with a balanced fertilizer. These dogwoods naturally grow with delightful symmetry and require little or no pruning./end/

I grow many of them and the Kousa Dogwoods and they are an easy tree to establish, although they are slow starters. Seems like forever before they begin to establish some height.
My soil is acidic, which they prefer and most of the trees are on a slope, which allows for good drainage. I don't have any growing in full sum, but there are some in my neighborhood that do and they are spectacular when in bloom!
My back door neighbor cut down a magnificant, healthy, 15'tall, pink flowering Dogwood and replaced it with a Bradford Pear tree. I no longer speak to the jerk!
Good luck with yours!
Rb

Did you plant it or did the landscaper? How was the root ball treated? It it was planted correctly, the dead branches might be the resilt of stress. It may take a year or two to get established before it really starts thriving.

they are not heavy feeders and if the plant is under stress, you should not fertilize it, that could be the final straw. If you are to use anything, make it an organic like Hollytone, which is formulated for acid loving plants like your dogwood

Question: Does anyone know if spraying a Pink Dogwood with milk and water can cure some molds like it does on Hibiscus and Mandevilla??