A population is a group of the same species. These populations come together to form a community. The community exists within an ecosystem that supports the lives of species that inhabit it. The ecosystem consists of the community of living species as well as the non-living environmental factors (air, sunlight, rocks, ground, etc...)that create the environment for the community. Biomes are a collection of ecosystems that similar environmental factors and communities that they can exist in the same geographic location. Biomes are large. There are 7 major biomes: coniferous forest, deciduous forest, desert, grassland, rainforest, shrubland, and tundra.
Here is an example. Suppose a family of squirrels has built a nest in an oak tree. There is also a nest of bald eagles in the treetops. Moss grows on the bark on the tree. The squirrels, the eagles, and the moss come together on this tree to form a community. This community along with environmental factors, such as rain fall, temperature, etc... make up the ecosystem for this community. When these ecosystems combine, they form the biome of a deciduous forest.
I have included a world map of the major biomes.