Homeless people sleep either on the street or in camps. Most have a little camp set up in the woods. A tent and a tarp are priceless to a person that needs a dry place to sleep. Since most tents tend to leak a little, a tarp is normally placed over the tent to keep it dry during heavy rains. A tarp can also be used to keep other supplies and gear dry. Providing some string or cord is also very helpful.
You would want to purchase small tents. A two man dome tent is perfect. I have found them at Walmart for $15 – $20. When they are on sale just buy all you can. Tarps run about $5 each. If you are on a tight budget then just provide tarps and string (cord).
Giving them out is simple. You simply ask a person or group if they need anything. If they need a tent they will tell you. You can also ask if they have a dry place to sleep. If they already have a place or if they are traveling through town they will often decline your offer. Also, you would want to remove the scan tags so that the tent cannot be returned.