I am a bit busy atm to type out a detailed list of questions and answers, so some of this may be redundant, but this is a list of things I put together that you need for a new set up. Given that you care for your guy as Petco told you, you might as well review it and fix things as necessary.
a) tank - you could start with a 20 gallon long, but your baby will need a 40 gallon breeder quickly, so might as well just start with that. If he is intimidated by that, you can partition it with some cardboard or something temporarily.
b) substrate of your choice (but nothing loose) - I would highly suggest slate tile. It is very similar to their natural habitat, is cheap, easy to clean, keeps muscles toned and nails trim. Other options are reptile carpet, non-adhesive shelf liner, and paper towel/newspaper. Your call really.
c) basking spot (rock or log, either from outside and sanitized, or bought)
d) hide (don't use this for the first couple weeks so your baby doesn't hide instead of bask and acclimate)
e) other tank furniture (a log, a fake tree, vines, fake plant... whatever you want. Just browse the pet store)
f) basking light (whatever wattage gets you to the right temps (105-115F basking spot, aiming for 110F). You can use either a clear household bulb or a basking light from a pet store. Just make sure the bulb is not colored or coated.)
g) basking light clamp lamp fixture
h) 3M command hooks
i) under cabinet fluorescent fixture (I got mine at Walmart - I had a heavier one from Lowes, but it kept falling)
j) ReptiSun 10.0 tube
k) Digital thermometer with probe (at least 1, and they should have a hygrometer built in to measure humidity) and/or temp gun
l) a food bowl for salad, and another for worms/roaches (no water bowl - they don't need a water bowl, and it will just raise the humidity. Just be sure to give baths. Do not feed mealworms a bearded dragon, but you can put phoenix worms, silkworms, dubia roaches, waxworms [treat], butterworms [treat], or hornworms [treat] in a bowl. Crickets will not stay in a bowl)
m) If the tank gets below 65F, another dome fixture and a ceramic heat emitter (do not use a red light)
n) (Optional, but really really useful) a power strip with built in timers for lights.
o) supplements - you will need a calcium with D3 powder to be used 5 days a week, one feeding each day for a baby. As an adult, this goes down to 3 feedings a week. You will also need a multivitamin powder. Use this two days a week, one feeding each day for a baby. As an adult, this will drop to 1 feeding a week. I use Rep-Cal and HerptiVite, but other options work as well.
p) If your ambient temperatures are not high enough, you may need an additional light fixture and a lower wattage household bulb to bring up the coolside temp and add extra light.
My other suggestions would be to look into starting a dubia roach colony. If not, find good, reliable sources either at stores or online for crickets and other feeders. Also, spend some time to locate a good herp vet in case of emergencies. Also, be ready to buy a LOT of bugs. Most babies eat upwards of 50 crickets or other feeders a day.