select @@SERVERNAME command of SQL

select @@SERVERNAME is used for get current server name if you not know your current server name then use this command
after installing SQL
the servername bydefault is your computerName\instancename
here computer name is Vaibhav-PC so servername bydefault is Vaibhav-PC\SQLExpress
if you not seeing any server name under browse for more=local servers then
try to login using .\instancename as serverName(ie .\SQLExpress)
and after login
run following command
select @@SERVERNAME
using this command you can get your login server name of SQL
so here is VAIBHAV-PC\SQLEXPRESS
replace .\SQLExpress as VAIBHAV-PC\SQLEXPRESS as server name while connect to server screen