Why won't the trigger pull back

So I got this for my little boy for Christmas. I know nothing about need gun in general. Didn't even know there was pages like this. Anyway the trigger will not pull all the way back. It just moves a little and it won't I guess lock or make the clicking kinda noise when you pull the thing on top back. I tried the orange button on the side but it doesn't do anything at all. I've been looking on Google but I haven't found anything that helps and for all I know I'm not looking it up right.