Create a GitHub account if you do not have one yet.
Upload your executable modeling project
generated files (Java sources in src-gen and class files in bin) must not be uploaded
switch off Build Automatically option in Eclipse (Project menu)
clean the project, but with Start a build automatically option *not* selected
see the tutorial if you are not familiar with git and GitHub
In the wiki page of your GitHub project give a brief description of what is your model about and how to start it. Add a link to the txtUML webpage to this description.