Some dyers strain the dye in a metal strainer with cheesecloth inside, just to be sure to remove any undissolved bits of dye that might spot the material. THE amount of dye should be in proportion to the weight of material. The directions that come with your dye will tell you about this, and about the amount of water. If you want a darker or lighter shade than the one the dye is made for, use more or less dye. There should be enough water in your dye bath to cover the material, with the folds well opened out.
Boiled dyes vary in method.
In some the material is put into the boiling dye. In others, the material is put in, and the dye bath brought to a boil. Be careful to follow the method that's advocated for the dye you are using. There is nothing so important in dyeing as just following directions faithfully. IF you are boiling material in a dye bath, stir it constantly, so that all the surface is penetrated.