Questions about red ear slider.?

I purchased my first aquatic turtle today, a red ear slider. I know the basics about taking care of them and have been reading about them for a couple hours now. i set up a nice 30 gallon tank with a filter, a platform, and a couple fake plants. does it take time for a turtle to get used to its new home? and i took him out to feed him but he wouldn't eat the food he just seemed more worried about running away. I'm trying to be gentle, make slow movement and be quiet to help calm him down. I just need a little help getting started. so please any information will be greatly appreciated. thank you.