Well done exactly, yes!
I'll save you the trouble and explain another, sometimes overlooked part of Genjutsu.
Genjutsu Layering is casting a secondary illusion upon your first one, with the resultant effect being a combination of said two illusions. The rules are: 1, the secondary illusion that you cast cannot be of a higher rank than the first, if so it will simply overtake the first one; 2, you are only able to stack up to two illusions, no more; 3, if both illusions are of the same rank, they cancel each other and nothing happens; and 4, the highest ranked illusion (so your first one) will be the overall rank of the entire illusion.
Any questions?
For now I just want you to perform the illusions as if you were to cast it on a random opponent.
( Magen: Kokoni Arazu no Jutsu ) - Demonic Illusion: False Surroundings Technique
Rank: D
Type: Supplementary
Range: Short-Mid
Chakra Cost: 10 (+5 if you use it double)
Damage Points: N/A
Description: The user casts an illusion over an area that allows him to manipulate the way an area looks to fool an opponent. He can only change the way the terrain looks, and not any other feature.
A simple illusion, by channelling your chakra throughout your body, into the air and into your opponents mins, you're effectively casting an illusion on him where you can change the environment around him. Albeit to a limit, you can for example make it so that he thinks the ground beneath him turns into sand, but you can't add extra features in. For example, you can't simply make a fireball appear into the air that descends down towards him. Though I love the fact that this technique requires no hand signs, meaning a normal opponent won't be aware of being caught within the illusion until after the effects have hit in.