I have a new fushia. It has one stem. It is not really growing. I have it in the shade. Could this be the reason
If you're trying to grow it in all-day shade it is probably not going to be happy.
Morning sun, and shelter from afternoon baking; or lightly dappled is useful. Mid range temperatures - not into the high nineties.
Free-draining soil with a fairly high level of good, well-rotted compost in the soil and used as a moisture-conserving mulch.
Not under evergreens with surface matting roots.
Moist soil that barely dries out - and isn't actually soaking wet.
Some Fuchsias are quite drought resilient - and others show their displeasure quite quickly with smaller leaves, dropping flowers and then dropping leaves.
If you're in a hard-winter zone and you want to keep your Fuchsia you can pot it up for over winter and keep it in a good light, above freezing or barely below (about 1-2 degrees of frost).
If you're in zone 9 it can stay out to become dormant, leaf-free, and perhaps frosted on the tips. It will come back again in spring.
In zone 10 it might slow down for winter but still be producing flowers and new leaves.