How to Name Amides

Make sure you have an amide, and not an amine (an amide has a C=O attached right beside the N)
Find the carbon chain that is attached to C=O. It doesn't matter which carbon chain is longest for amides.
Create the root of your molecule name: The amide on the right has two carbons on the side with the C=O, so the root is "ethanamide"
Add substituents as required. If there are carbon chains on N, you'll use "N" as the number. In the molecule on the right, there is a two-carbon chain attached to N, so we'd add N-ethyl to the front of the molecule name.

Amide
C=O beside the N

Amine
No C=O beside the N

Examples

The carbon chain with the C=O is five carbons long, so the root of this molecule name is "pentanamide".

Then, we have an F atom (fluoro group) attached to the N, and an benzene ring (phenyl group) attached to the N as well.

The molecule is N-fluoro-N-phenylpentanamide

The carbon chain with C=O is five carbons long, so the root of the name is "pentanamide".

Then, we have:

three 1-carbon chains (methyl groups) attached to Carbon #2, #3 and #4
An F atom (fluoro group) attached to the N
A 7-carbon chain (heptyl group) attached to the N

N-fluoro-N-heptyl-2,3,4-trimethylpentanamide

The carbon chain with C=O is four carbons long, and it has a double bond starting with carbon 2 on the chain. The root of the molecule name is but-2-enamide (Notice the "ene" for the double bond)

There are two Cl atoms (chloro groups) on the N This molecule is
N,N-dichlorobut-2-enamide.

Also note, if you know about cis/trans or E/Z, then the real name for this molecule is
trans-N,N-dichlorobut-2-enamide or
(E)-N,N-dichlorobut-2-enamide.