Species
Siberian Husky dogs, A species. :http://siberianhuskysite.com/
So, as said on the vocab page a 'species' is just that, a species. A group or classification of a certain type of organism. For example, A dog is a species, but so is a Siberian Husky.
Population
A manatee that is part of an aquatic population
:http://www.public-domain-image.com/
a population, in really simple terms, is just one species living together in a single area. for example, a Manatee is a species, But a of Manatees off the Florida coast of the Atlantic Ocean is a community.
Community
An elephant seal in its native community interacting with penguins. :www.dailymail.co.uk
A community is a step up from a population. It's a group of different populations living in the same area. For Example, in this picture we hae a population of Elephant seals and a population of penguins living together in the same area. That's a Community.