codlink:
To be honest, if you ready to design your own board, you shouldn't need to ask these questions. But I don't have the Mega schematic with me since I am on my tablet. I will get back here tomorrow with the answers.On a side note most of those are statements, not questions.
codlink thanks for helping
I ask these questions because want to know about this components and how to use it in the circuit before I start design my own PCB,
I will not use program like CADSOFT EAGLE of Altium Designer or DipTrace it's not free, expensive and little difficult
there is fritzing and PCBWEB , 123d.circuits.io , EasyEDA all these sites beside fritzing software is free and very easy to learn for beginner and people who never design PCB before I can place the components as what in Arduino schematic and make some changes in design and PCB color but this will not tech me anything about electronic, I want to know how to use the component I download Proteus software to use the components and make some simulation to make my own connection for it and understand the using of capacitor in the circuit, but in Proteus 8 I didn't find some components like LM7805
so I'll try so use Multisim and hope these power components included in the software.
I waiting your answer.