how to import megamu.mesh.*; in eclipse?

i had a processing program,
in which i typed

  import megamu.mesh.*;

now i'd like to edit it in eclipse, after i did  follow what the guide said.. like.. import ' core.jar ' and add it to java program build path..
i find i can't import this package into my program in eclipse.

maybe i should import some other files into my eclipse java program ..like xxx.jar
but i don't know what should i do excatly?

thank you all > <