CartoDB's goal is to be the "Instagram service for maps". They make it easy to make attractive maps, even without knowledge of sql and css. However, to take advantage of its full power sql and css are invaluable.
Pros: Default maps are beautiful, very powerful
Cons: Free maps must be public, more limited free storage, mostly relies on a basic knowledge of sql and css
CartoDB is browser-based, and so is very easy to access from any computer with internet.
From the CartoDB home page, click Create your first map. You'll be asked to create an account. After you have done so, you should find yourself at your "Dashboard". From here you can create new maps and edit those you have already made. You're now ready to start the tutorials below.
To show off what CartoDB can do, we're going to make a map of the world's countries and their populations.
1. First, download the data set from here.
2. CartoDB makes it easy to upload your data. On your dashboard, click Create Table. Drag and drop the file you downloaded into the space provided.
3. It may take a few minutes to upload. Once it has, you should be presented with table of countries with geographic locations and population numbers. To see it as a map, click Map View. You should see an orange map of the world.
4. Since we have the data to do so, it'd be nice to see the populations of the countries, so let's make an intensity map. Click Wizards on the sidebar, and then select Choropleth.
You should see a warning that there are no numeric columns in your table. Right now, CartoDB sees your population column as a list of letters, instead of as actual numbers. Let's change that. Going back to the table view, locate the "pop2005 column". Using the drop down menu, change the data type to "number".
5. Go back the Map View, and the Wizards, and try again to change the map type to Choropleth.
Done! You should see a map like the one above. Now that you've familiarized yourself with CartoDB, try some of the tutorials below, or mess around with some data of your own.
The CartoDB website has some great tutorials for familiarizing yourself with the software. Try starting with "Creating a simple points". From there, you can look for the tutorials that fit your specific needs. Note: After each tutorial, you may need to delete the map you've created before making a new one. CartoDB severely limits your storage space.
For more tutorials, you can try github.