Introducing my self (and some noob questions)

[Herps 4 Life]

Greetings to all!!!
Hi, my name is Alessio(but just call me Al ),I'm writing from Veracruz,Mexico,but I'm italian(ok,but don't start imaginating here the classic stereotipical italian with the weird accent and all,lol), and I've just joined the forum! I always had a remarcable passion for herps since I was 4,have been keeping a variety of invertebrates & amphibians over the years(I'm own a grammostola rosea rigth now too),and i have been into tropical fish hobby for like 8 years. But most important,I'm also new to garters! Recently I was having a walk in the city, when in a petstore suddently I saw an announcment saying "Serpientes de Agua" -water snakes- and saw 2 tiny snakes with a familir yellow and black striping. Garters!(curiously,i've been looking for them for quite a few years,WITHOUT SEEING ONE o_O ) The poor things were held simply in a plastic jar filled with water! I felt my coscience moved then. So, a couple of days later, I went to buy one(I'd loved to bring them both home,but after some discussion, I had the permission only for one snake,sadly). I love it! ^^ I've been keeping him for two weeks now, but I still have some concerns(yes,I had done all the research before,but even then,problems seem to find their way as always) :
1.still not shure about the species(the closer ones I have founded in some photos were forms of sirtalis,but also spotted similar radixes..I'm so confused) 2.WORSE, still not got it to eat! I'm pretty shure he didn't eat anything in the store, and it's starting to get skinny!!! ): Help!
some details: I'm temporarly stabulating him in a 30x19x16 ehm.. well sorry, don't know the term, but.. a transparent plastic box, with escape-proof holes drilled in the lid, a hidebox(not used very much), water dish and paper towel substrate. No heatpad or heating bulb, since normally room temperature is already well above 30c, I don't want to cook it!(yes,pretty hot all year around here) The temperature drops to about 26-27c by nigth. I had started the taming "process" from after 5 days that I had it; and I'm amazed for how quickly he's calming down,with notable daily progress! I couldn't find yet earthworms, and didn't saw a single pinky in petstores (!?), so all I'm offering are guppyes,alive and dead. With no response. I'm considering to start force-feeding him tomorrow, I don't want to see him loosing more weight and energies, but I'm really afraid of hurting him, they are so fragile! also tried with crickets,read that sometimes works, but noting. What should I do, I'm already very attached to the little guy, I don't want to see it going down like this!!!!
Thank you very much for any response! -and sorry for the large (huge) post! p.s. some pics:
[ATTACH][ATTACH][ATTACH]hidebox.jpg[/ATTACH][/ATTACH][/ATTACH]

the photos are a week and a half old