The krazy2 source code checker at http://ebn.kde.org/krazy/reports/kde-4.x/kdeedu/marble/index.html lists several spelling errors in section 28. "Check for spelling errors". To fix them

• Check out and compile Marble as described in https://marble.kde.org/sources.php
• Use an IDE like QtCreator or some other editor to open the files with spelling errors and fix them (consult an dictionary like dict.cc in doubt)
• Recompile the code and make sure it still compiles fine
• Create a patch using something like "git diff" and submit a review request for the marble group at http://git.reviewboard.kde.org

Please join the #marble IRC channel in Freenode. Earthwings, tackat and any other Marble developers are happy to help you with any questions that arise.