How do we configure SAN storage on Blad server for the first time? After we install the ESXI software, how will we install VCENTER as a virtual Machine?

1st of all  , create a dedicated LUN for every ESXi host:

(if you have3 blades , create3 LUNs :SRV1--> LUN1 ,   SRV2-->LUN2 ,  and SRV3-->LUN3).

this will be used to install the ESXi vShpere operating system for every blade.

Then, create the RAID groups and LUNS and assign them to your all ESXI hosts (you may need to create a RAID10 for database guest machines for example , and RAID5 for web servers guest machies ….) 

Once when you finish the installation of ESXI on all your servers ( install the system on the dedicated LUN you created first)  , open your browser , and type the IP address for any ESXI host ( i.e : https://192.168.1.1 where the192.168.1.1 is the ip address of one of your ESXI hosts)

It will provide you with a download  link .Just install the VMware vSphere Client and launch the application.

Enter the ip address and user name (root) with the password you configured during the installation of ESXi 

Then you can create your vCenter virtual machine using either ready to use virtual appliance can be downloaded from vmware website or  you can create a windows machine , then install the vCenter on it.

By the way , vCenter is only useful when you have more than1  ESXI host , in other words (when you have cluster) for the sake of high availability, fault tolerance , DRS , vMothin , Distributed switches, centralized management , Data Protection, SSC etc….. All those features are available with vCenter & multiple hosts  , and it make no sense to install vCenter on a single ESXI host.