Your round container is way to small they have no room to move around. Chicks grow fast very fast. Your heating pad like you have it can also burn them since they are so small just laying on it. If you look at my set up you can see the heat lamp. Place a thermometer at the bottom of your container and turn on the light. Let it heat up and keep a eye on the temperature till it stays at 90 degrees. If its higher move the light away a little bit if its to low move the light closer to them. If the temperature stays at 90 degrees for 4 hours you should not have to adjust it again. Make sure you keep a close eye on it while your waiting your 4 hours. till its time to change the temperature again by 5 degrees lower each week. Once your chicks are at 70 for that week and its time to drop it once again you can turn off your heat lamp. They should not need any more heat. Make sure you put shaving in the bottom of the container as well as everything they need feeder and small shallow water. Place marbles in the bottom since silkies are small birds. This will help them so they do not fall in it. Place some blocks that are cut from a 2x4 into the middle of the container this gives them something to explore and play with. Later you can make a small perch that they can learn to roost on taking two blocks and a longer piece and nailing or screwing them together. The black container I have under my water dish is so they don't get water all over the shavings as well as shavings in the water. Once they are a little older I will turn over the container and place the water dish on top of it. The chicks you see in my picture are just going on a week old.
Pasty butt is when there is poop stuck to their vents and you wash off their bottoms and dry them off. Then put them under the heat lamp on the shavings and let them dry off. Making sure the vent is clear in order for them to be able to poop once again. This is very common and has to be checked for a few times a day if you know one has a pasty butt. Do not use hot water on the chicks just luke warm almost room temp. If you need use a soap try using Dawn. Its gentle will not hurt the chicks. I hope this information helps you some.

