Welcome to res. :) There's probably more newbie guides around but I'm at a loss to name them. D':
I'll just brush up a few points for you here instead.
To feed a pet, go to your profile and "select" the pet you want to use. The select option should be directly under the pet's image. Then go you your inventory, select the food itemm you'd like to feed and select "Feet Pet" or "Use item". The amount your pets hunger decreases depends on the food. I find the cheap pizza's are the best for the price. :) You can find them in "Antonio's Pizza" on the Shop List on the nav bar you see on the left hand side of the screen.
Another option is to open a food pen. To open a food pen, go to the top nav bar and click on the icon that looks like a gate with an apple in it. It's the fourth from the right, on the left of the money bag. Food pens automatically feed your pet once a day as long as your pets hunger is "full" when you get them. If they are below "full" you'll have to feed them yourself to "Full" and then the food pen will feed them at reset. :)
The battle system currently isn't working, however you can still train pets in preperation for it. To train a pet go to the top nav bar and click the dumbells. Strech and warm up before you train! It's pretty self-explanitory. ;)
To get TU, Try playing the mystery bag game, and other games for TU. You can also buy and sell items if you're a merchant, or sell pets if you are a rancher. If you have some rare or well-named pets, you can usually make a pretty penny from them!
Rescreatu also has some events from time to time, like seasonal egg hunts. Unfortuneatly you just missed the halloween seasonal egg hunt, but there is another coming up on christmas! Be sure not to miss it! It's a great opportunity for making TU and getting rare pets and items.
If there is anything in particular you'd like to know or need help with, you can mail me, or ask in the Shout Box [Chatroom] If you're 13 or older, and usually you can get help there as long as you follow the SB rules. :) Have fun, and enjoy res!
There are also staff here to help you if you need it, a list can found here:
http://www.rescreatu.com/forum/cat/general/introductions/staff-list/~page/1/