GeoCommons is a browser-based mapping tool. It has some nice features, but takes a little while to get used to.
Pros: Easy to symbolize using the data, can view data and map side-by-side, nice user controls for sharing, data searching
Cons: You don't have control over labels, nor over the contents of the info windows, interface takes some getting used to
First, you'll have to make an account. From the GeoCommons homepage, click Sign up for Free and follow the instructions for making an account. Once you've made an account, it might be worthwhile to experiment with the maps and data search on the homepage. Once you feel ready, try one of the tutorials below.
We're going ot make, and customize, a map showing the urban areas of the world.
1. To start, download this shapefile as a zip. Locate the file in your downloads. Right click and select Extract All.
Select a location for the extracted folder.
2. Now that we have our data, we need to upload it to Geocommons. From the Geocommons homepage, click Upload Data in the upper right hand corner, and then Upload Files. Click Add File, and navigate to your extracted data. Select all the files inside the folder, and click Open.
3. When all the files have uploaded, click Next, and then Next Step. It will ask for information to help Geolocate the data. Select "Use the existing geographic data". Geocommons may take several minutes to process the data. When it's done, follow the steps to review and publish your data.
4. Click Make a Map. Double check to see that the table you uploaded is listed as a layer. If not, click Add, navigate to Your Datasets and add the file as a layer. Urban areas should show up on your map. At this point, here's what your map should look like (zoomed in on Europe):
5. Let's try to make the map prettier using some of Geocommons' customization options. Geocommons allows you to change the basemap (i.e. the map behind your data). To do this, click the green Change button next to "Acetate" in the window on the right side of your screen. Try a few different options, to see what you like. Personally, I like "OpenStreetMap (Road). It can make some areas, particularly Europe, look cluttered, but I like that you can see the highways connecting major cities.
6. Now, let's see how you can change the color of your markers. click on the the name of your table in the "Layers" section of the same window and select Style. Click Color and try a few different ones. Try to find one that makes the urban areas pop, but doesn't clash with the basemap you chose. Once you've chosen a color that you like, we're going to try changing the borders of the areas. In the style window, click this logo:
Try changing the line color, thickness, and transparency. I like white borders, thickness 1, and transparency ~15%. After you've done this, you can try messing around with some of the other options. When you're done, click Save in the upper right hand corner. Congratulations! You've made a map! Here's what mine looks like after following these steps:
GeoCommons provides minimal documentation, and so tutorials from outside sources are most useful.
Here's a good one for getting started. It teaches how to upload a data set and make a simple map of points and an area map.
These set of video tutorials go into more depth on customizing your maps.
If you're looking for an answer to a specific question (e.g. how to search for data), try the GeoCommons User Manual.