All app icons not showing up in my home screen I have a Spice Mi-429 which I bought a few days ago. Since I was not an android user before buying this phone, I am unable to understand some features of the phone.

This phone is Android Kitkat 4.4, 1Ghz Processor, 512MB RAM, 4GB ROM.

Currently I am unable to set the icon shortcut of apps in home screen. Apps like Hangouts, YouTube, GMail are not showing up on the Home screen since they are already installed. I have to go to App Manager > All Apps > YouTube > Launch them.

Can anyone help me with it???

Here are the screenshots of my phone..

   

Click images for larger versions
the apps on the homescreens in Android are to all intents and purposes shortcuts, and not the apps themselves. 

You should but don't have an icon in your dock (the lowermost part of the homescreen) that opens this app drawer.

The icon usually looks a bit like this: 

http://cs3-1.4pda.to/4714358.png

This image shows: Google Now, then your homescreen, note the middle icon on the bottom, and then the App Drawer opened (very right of image). This is the list of all your applications. 

You could try (I don't have a similar device) long pressing on a free part of a homescreen and see if you can add an action, or shortcut to the app drawer. 

Alternatively a launcher like Nova Launcher or indeed Google's own "Google Now Launcher" are free and have this option. 

Here is an example of adding an action in Nova Launcher which might help point you in the right direction (note app drawer):