HumboldtJSDOM is a library that can be used in conjunction with Humboldtjs to provide code completion and compile-time syntax checking on the HTML DOM.
Usually you will only want the bin/HumboldtJSDOM.swc and dom folder and drop that into your project. You can safely ignore the rest of this repository. The rest is only needed if you want to change the default DOM bindings or improve on them.
Unless you want to do these things you are probably better off starting with the HumboldJSEmpty project, so check that out first.
After cloning this repository you can import the folder as an existing project in Adobe Flash Builder. This may not be needed depending on your usage scenario. Actually building the library is done by running the ant build script in the build folder.
Note that you may need to update the FLEX_HOME path in the ant build.xml