mightymike,
Just finished doing this with Steam on Civ V and just made and saved my first map. Not anything to brag about, just got my toes wet. Under Steam, I fly by SeniorBirdman in case you are interested. The Civ V game manual covers ModBuddy and WorldBuilder SDK on page 195 of the game manual. However, it took me quite some time to actually get to a position where I could download the needed SDK and then some additional time to write down all the required steps. Lets hope I don't forget anything important.
Go to Steam and select the Large LIBRARY button at the top left.
At the very top of your screen you should see from left to right "Steam', "View", "Friends", "Games", and "Help".
You need to click on "Games" and select "View Games Library".
Under the Large LIBRARY button, which should be well lit, you should find something immediately below it depending on your most recent usage in that area. No matter what it is that appears, there will be a small triangle just to the right of the text with a corner pointing down. You want to click on the text or the triangle (either one has worked for me), and then you want to select "Tools", which is one of the 7 choices that appears.
Then a lot of items appeared. Close to the bottom you will find one that starts out with "Sid" and ends with "SDK". The words in between should make you happy. You will need to accept an EULA before you can download ModBuddy and WorldBuilder.
After installing the SDK, you will find what you need under "Installed".
Hope this helps.
