Glad to meet you, Mass Neighbor, Sue, and welcome to BYC. You have some better advisors than me for that poor chick. I send best wishes for that little one.
Here are some articles from our archives that may jumpstart your collection on chicken ailments and cures (though I am not sure any will cover a broken leg, you might find advice there).
1. Chicken ailments (an aging index to articles written over the years about chicken illnesses. Be aware that some of the links dont work and some of the authors have disappeared from BYC. The date of the index is 2012! Nothing else as comprehensive) and this updated Chicken Illnesses Library
2. Chicken First Aid Kit (again, an older article, but a good one; there have been a number of more recent posts discussing this here and here, for instance)
Here are my favorite beginning articles that helped me as a newbie. All articles are short, and have illustrations, and reviews, which are often worth looking at for the comments.
3. Ventilation (important to chicken health), with helpful links to coop designs organized by climate (because what is just right for my New England hens won't work for my brother's Arizona chickens)
A. Use the SEARCH button, but use the Advanced Search choice, and select ARTICLES at the top of the box. Just enter your keyword(s) and scroll through your results!
B. I find it helpful to notice the rating and reviews. All articles are by BYC members, and all the reviews/ratings are as well. The ratings help a newbie like me sort the most useful and reliable articles.
C. You can bookmark the articles or posts you think you want to refer to again using that bookmark icon at the top of articles or posts. You can find them again by clicking on your own avatar and looking at the list of bookmarks you have built up!
Notes about where to put a coop:
1. As far as you can, put a coop and run on high ground, that drains well, so you won't have so much muddy coop problems. Chickens need to be dry, dry, dry.
2. As far as you can, put a coop with the ventilation lined up with your prevailing breezes, and away from the direction of your storms. If you are not sure of these (who is these days?), check with your local National Weather Service website.
3. As far as you can, arrange for some sort of shade over your coop and run. Preferably deciduous so the girls will enjoy winter sun, but summer shade.