We need to use ADAM as our asset repository with Tridion 2013
what all we need to start with?
The first thing you need to sort out is an ADAM license of course, then you should contact your SDL Web sales/account manager for obtaining the license and software for the ADAM Web Service and ADAM ECL Provider. These are custom parts delivered by SDL, allowing you to create a connection between the two systems.
Then from there just follow the documentation as @Raj suggested, you will automatically get to the topic of creating the required certificates and it is explained where to place them.