Hi Dee,
If you just walk along Main Ave in Durango you will see many rafting outfitters that cater to the tourists coming in. You can also grab a flyer for some in any of the Hotel Lobbys. Also, the welcome centers on Main or a bout 2 miles south at Santa Rita park can point you in the right direction. Although the Animas River is not a particularly rough stretch early in the season it can get nasty from snow melt in the mountains. Check with the outfitters in regards to your 14 year old. Have fun!