There are numerous sources of information for both the population and the community that you want to reach. Here are a few:
1. Organizational Websites
As mentioned above, an organization's website can be a great indicator of whom that organization serves. For instance, look at Daniels Spectrum "About" section: http://danielsspectrum.ca/about-daniels-spectrum/
Here you can learn where the organization is located, that it is meant to function as a community hub, what customer service standards it meets, and what services it provides.
2. Community Statistics
There are numerous websites that are easy to use and that can help you find additional information about the make up of particular neighborhoods. Here are a few:
a. Scarborough Census Profiles
b. Toronto Census Profiles
3. Governmental/Municipal websites
The City of Toronto also provides a lot of information regarding neighborhood demographics:
1. City of Toronto - Data, Research and Maps - Neighborhoods and Communities
2. City of Toronto - Data, Research, and Maps
3. Wellbeing Toronto