Sand or gravel? I want to put gravel in cut of my backyard...itty bitty...

I want to put gravel in cut of my backyard...itty bitty gravel. It will be in the way of walking way and around my junipers. My neighbor say I should put sand down then gravel or basically sand only. I own dogs and I am worried that flees will like the sand so I resembling the gravel better. I am not a gardener type person at adjectives.
This whole nouns is about 50x50 and it is the nouns that my dogs poop and pee in.

Is it okay to freshly put down a bunch of gravel or do I need to prepare the nouns?

I was hoping I could merely dump a bunch of gravel on the area..it is a exceptionally hard dirt nouns right now.
Answers:    I similar to the little multi-colored cobble stones.They feel better on my paw.Follow everyones advice going on for the weed barrier.You should probably dot out your area w/stakes ,and string so you enjoy a guide to go by.It'll be approaching a giant litter box.You got alot of animals,huh?
I would use pea gravel or smooth river gravel near NO weed barrier. My brother used crushed gravel over weed block and his dog pulled up all the weed railing the first day. Later the sharp gravel would cut his paw and bleed all over the house. RScott