Weeelll. I don't have a tutorial for this but I do have tutorials on my site: www.stayinwonderland.com
Nah, you'd never want to model grass really, just get some pre-modelled stuff from the various web sites. But the background trees are free with the plug-in 'forest pack lite' which is free when it's limited. Same with trees, better to buy them or find some free ones. No need to make them.