Beautiful Maryna!!  Those petals are so perfect!

fabulous drawing. Really good atmosphere. I can almost hear the horses running

there are various ways to gain some control.
The first is what I used for my astronaut series - I used masking tape to create a wall by only sticking half the tape down and bending the other half up.
Another is to only pour in a certain area, eg. pour a stripe of sky colours, then a stripe of sea colours, then a stripe of sand colours horizontally across the canvas to form a sea scene. You could then use a stick or panting knife to break the edges / form waves.
another is to pour the background very carefully. Think of your dragonfly example. Pour around the lines of the dragonfly to create the background. Us a stick or knife to gently move the paint closer to the edges. You can then gently pour the wings and body using their colours in the correct places. Again using a knife to coax the paint into the correct shape. The paint will probably runn a bit messing up your edges, but that doesn't matter. Once dry you come back and add nice flowing black lines to indicate the shape. You would then end up with an artwork looking something like THIS

You could also do the artwork in multiple stages. Pour the body, dry it, mask it off, pour the wings, dry, mask, pour the background. This would take a long time, but you could do several at once to make up for the dry times. If you use this technique, be sure to thoroughly clean any silicone off the area you want to pour over a second time atherwise the paint will not take.

fantastic, we love to see how you guys grow as artists. Over the years many of our students have turned their passion into a full time income. You are doing a fabulous job Maryna

Don't forget to post your challenge painting