How can I get Name of all apex class having api version less than 36 in my org? We need to upgrade classes having older api version.Please guide us regarding that.
It's better if you create a view in Apex class section in your org. There you can filter the classes by applying filter based on ApiVersion of classes.
Other then this you can perform Query also on ApexClass Object. The following Query would work for you:
Select Apiversion,Name from ApexClass where Apiversion<36