programing problem HELP

stan siems

I have a lightaprs w I just received and am working on programing it.   I down loaded and installed the driver, installed the latest Arduino pgm. As instructed I open Arduino go to preferences  type in the address for mightycore  go to tools -board manager and the down load is not there! and there is an error message that it failed to download. What am I doing wrong!

Thanks Stan