Create a user defined table type in c# to use in sql server stored procedure

Simplest option is to create a DataTable in C# code and pass it as a parameter to your procedure. Assuming that you have created a User Defined Table Type as:

CREATE TYPE [dbo].[userdefinedtabletype] AS TABLE(
    [ID] [varchar](255) NULL,
    [Name] [varchar](255) NULL
)

then in your C# code you would do:

DataTable dt = new DataTable();
dt.Columns.Add("ID", typeof (string));
dt.Columns.Add("Name", typeof (string));
//populate your Datatable

SqlParameter param = new SqlParameter("@userdefinedtabletypeparameter", SqlDbType.Structured)
{
    TypeName = "dbo.userdefinedtabletype",
    Value = dt
};
sqlComm.Parameters.Add(param);

Remember to specify SqlDbType.Structured as the type of parameter and specify the name you have used in creating your UDT.