According to IUPAC , Amides are derivatives of carboxylic acids. The carboxylic acid have -oic acid -ic acid as their suffix which is replaced by -amide in case of primary amides. Example- Ethanoic acid in carboxylic group but in amides it will be ethanamide.
In naming the secondary amides. The nitrogen atom present in the alkyl group is denoted by upper case N, while the alkyl group attached with nitrogen are presented as the substituent of the compound.
Tertiary amides are named in the same pattern just like secondary amides but it include two N,