Note that Search Records allows you individually source multiple people on the same record by attaching it to one person, clicking the next member of the family and attaching it to them by name, etc. This is the preferred way of using sources.
Tree Connect does not seem to have that degree of specificity, you may need to identify the source as "James Watson household in the 1852 census, Edwardsburgh, Grenville, Canada West.", and then use the Source Box to attach the same source to all the members of the family. Tree Connect saves time and work.
Sources are records that prove events and relationships, or provide strong evidence of them.
Sources may be classified in these ways:
Primary sources are records created at or about the time of an event using information provided by someone who was present when the event happened. e.g. birth certificate or marriage certificate, christening record from a church register
Secondary sources are records created at a later time. e.g. a census may be a primary source of relationships but a secondary source of birth information. A tombstone likewise.
Original Sources are original documents or photographic copies.
Derivative Sources are transcriptions or partial transcriptions of the document
Many good books have been written on sources. See Evidence Explained, by Elizabeth Shown Mills
Creating Sources in Family Tree
1. The easy way is to click Search Records on the Person page, find and Attach the source document.
2. An Alternative is to click Create Source in the Source area of the Person page and follow the prompts. This is much more flexible, as it allows you to use documents that are not online.
3. Tree Connect is a free tool that simplifies attaching online sources that come from online sites outside of FamilySearch, to Family Tree. Go to http://recordseek.com/ and drag the Tree Connect icon to your browser's bookmark/favorites tool bar. Then when you find an online source you want to use, click on the Tree Connect bookmark, and follow the prompts to attach that source to the person.
The Possibility of Error
Even using the best sources does not eliminate the possibility of a mistake, but it sharply reduces that possibility. I had one line “proven”, based on finding the birth, marriage, and death records of my ancestor Elizabeth Goldring in a rural parish in Sussex, England. Then I received a photographic copy of a will that proved that the birth was for a different Elizabeth Goldring, who married in a different parish. Even using good sources, I had made an error. The marriage and death sources were for my Elizabeth, but the birth source was for someone else.
We do the best we can with the information available, and make corrections as needed.
What Should Be in Your Source Citation?
A source should identify the individual, the type of source record, where the record is found, and the key contents of the record. It should allow other researchers to find the same source.
Durability of Online Sources
Personal websites can have some of the best information one day and disappear the next day. Company and government websites tend to be more durable. FamilySearch has said that they will never change the URLs of the documents in their Historical Records collections. Some online sources are only available to paid subscribers. Get in the habit of quoting the key information as part of the source citation. That way the information will continue to be available, even if the source record disappears.
FamilySearch encourages the use of sources, but they are not required when reserving temple work.