How Can I get My Microphone On My Laptop To Work?

Today I got a Dell Inspiron ( Mod no. 9770H ) and I downloaded Skype to video call my girlfriend and she told me she couldn't hear me , I have tried googling plenty of things but nothing is helping me.
I have tried disabling and enabling the microphone and everything.
( By the way I want to use the built in mic that's in the laptop )
The sound bar doesn't go up when I speak.
I have Windows 10 already installed when I bought it.
I am so confused and I really need help with this !