Putting stuff in your own FamilySearch source box is good and all but until you have attached your sources to the people on Family Tree your work is not done. See like I explained these sources will work wonders to both make sure that two people aren't being assigned to the same source and that two conflicting records aren't applied to the same people (either would show that clearly those involved are talking about different people).
Anyway it's pretty easy I'll show you how to do it right now!
First you find the person you want to attach the source to using Family Tree. Click on the individuals name and then click "View Person".
Then it's a little further down on the individuals page but there is a section for the source box
And here's the source box view so you just "Attach" any of the sources which apply to that person and then forever that source will be linked to that person. And the word attach will be replaced by a paper clip symbol - which is a device used to hold paper together. How fitting right?
For those of you who still haven't registered to try out this new feature of Family Tree Click Here and do so! This will be the feature through which Family Search will be moving too so you might as well (Note: For some areas/types of accounts I believe this feature is restricted while they work out the final kinks and bugs)