Why doesn't my tablet work?

How can I make my tablet work? It turns on but won't connect to the internet half of the time it says the WiFi is not in range when I know it is. The 1mobile app for downloading apps will not load it constantly says network error. I tried to update and it says "please make sure you have updated.zip in nand or sd card" I have reset the tablet completely and nothing works please help me. I feel like I completely waisted my money on this thing.