The DeKalb County land lot maps are available online in PDF form from the DeKalb County Tax Assessor's office.
All of them are in this "URL format":

http://web.co.dekalb.ga.us/PropertyAppraisal/maps/18313.pdf

Simply put the land lot number that you need as the PDF name.
If you don't know the number of the land lot that you need, go to the DeKlab County Tax Commissioner's site (http://web.co.dekalb.ga.us/TaxCommissioner/tc-home.html), then click on "View or Pay Property Tax". Use the form to enter a partial street name, and then click on any of the results that are on the street that you need. Go to the lower left corner of the property details page, and click on the link to the property map. That will give you the same map, but for the land lot that your address is physically in.

David