Open the Crafting Table
Place 6 matching blocks in the crafting grid
Arrange them in a stair shape
Take the stairs from the result slot
Use the stairs block to place them in the world
If needed, mine and place them to rotate the direction
For wooden stairs, use planks
For stone stairs, use cobblestone, stone, or other stone variants
For brick stairs, use bricks
For nether stairs, use the matching nether block type