Dynamic CRM new fields

Some new fields were create in Dynamics CRM.

Now need to push some data to those new fields from asp.net website.

Need to add those new fields to:

[assembly: Microsoft.Xrm.Sdk.Client.ProxyTypesAssemblyAttribute()]

namespace Xrm

how should this be done? I read that these is a tool that generates this class file (CrmSvcUtil.exe).

But I do not understand how this would work.

Is this something that need to be done through Dynamics CRM admin?

Please advise.

Thanks