D visa cover letter.

My wife and I are currently the cover letter for her "D-visa" application.
Has anybody got any sample letters I can you as a template?
I'm unsure of exactly what they want us to write.
I have covered the reason for us moving back to ireland.
That we will not be a burden on the state, y having private medical insurance and enough funds to get us through the first year at home.
After that I am unsure what to say.

any ideas/suggestions?

Regards,

Kevin