Ferns are some of the most ancient plants on the planet, with more than 12,000 species discovered the Stag Horn fern is one of many similar species which grow originally on other plants in the wild. They are know as "epithytes" that do not require soil to live but instead anchor to trees. They produce new plants through shedding microscopic spores which form on the base of the plant like small brown dust particles. So don't wipe off those brown spores this is nature re producing.
The leaves are called "fronds" in the fern world and these particular types are called "stag horn" because they resemble the antlers of a stag. The other part of the plant is the brown disc-like dry leaf at the bottom of the plant called the "shield frond" protecting the roots of the plant and keeping it's nutrients and water inside safe. Do not remove this disc it's perfectly natural.
Potting on: You will need to remove your fern from it's young pot in soil as it matures and grow it onto a piece of wood inside a hessian sack hammock pinned to the piece of wood. This emulates it's natural habitat as the plant does not want to live in soil, it is an epithyte.
Watering: Usually once a week. It can be misted often using a fine spray bottle. Use a humidifier in your home if you have one, they also do well in bathrooms with some natural light. In the winter water a little less often. If the position of the fern is close to a heat source then watering will be increased to at least twice weekly.
If you have your stag horn fern mounted onto a wooden board, you can remove it weekly to soak in a container of water for 20mins before placing it back into it's hessian sack.
Light: Bright indirect Sunlight, avoid too much shade, these plants need dappled Sunlight.