since i was diagnosed wit autism ive felt kinda depressed

since i was diagnosed a few months ago with autism i've felt kinda depressed because its made me realise why people avoid me and id really like to be able to do things without seeming like an idiot or a child as im nearly 15 yrs old so i would like some advice on how to concentrate and not seem like a idiot or child, i really can't take much more im starting to get really upset.