Take apart the crib, if it is assembled already, to get down to the most basic pieces, such as the four sides including the legs and the bottom. Move the pieces to a well-ventilated area or outdoors.
Sand over every surface of the crib with sandpaper to lightly scuff the surface and allow the stain to adhere to the wood. Vacuum the floor and the crib pieces to clear dust from the area.
Spread out newspaper or cardboard onto the ground or floor. Lay the individual pieces of the crib out over the cardboard in a single layer. The pieces should not touch. Open and stir the can of stain to mix colors that may have separated on the shelf.
Apply the stain with a paintbrush in long strokes over the crib pieces, working in the direction of the grain of the wood as much as possible. Cover the entire surface of each crib piece with stain, flipping the pieces over, if needed. Make sure stain has made it into corners, along edges and into any detail work of the crib and add more if necessary.
Wipe a cloth rag over each piece of the crib while the stain is still wet to remove any extra stain. Wipe a second time with a new rag in the direction of the grain.
Allow each piece to dry once it has been wiped over twice. Check the specific brand of stain you used to determine drying time because drying time can differ among brands. Reassemble the crib once you're certain all pieces are thoroughly dried.