Whatever you chose, be sure their heat is on one end, and the other end is where you put the food/water and should be ambient temp there. Having a thermometer will help you immensely. When you first put them in there at a day old, they should be at 95F, and can go down 5 degrees per week after that.Ahh ok I see now before the picture werent showing! How do you use a heater with that?
Here's a link to the original Momma Heating Pad, otherwise known as heat cave: https://www.backyardchickens.com/th...d-in-the-brooder-picture-heavy-update.956958/
Here's a link to the same thing done a little differently in case you need more ideas. https://www.backyardchickens.com/articles/how-i-made-a-mama-heating-pad-plate.74953/