Get a long handle, a light weight broom or sorting stick with a flag or a paddle. Chickens are pretty habitual so this will get easier. Anyway let them out, walk over shaking your red treat can with a bit of scratch in it and throw it on the floor of the pen you want them in. Then circle around the flock with your stick, now many people think fast is the way to go here, but trust me, a being slow now will be faster in the long run.
Stand with the chickens between you and the gate you want them to go through. Stand there not moving just with your arms and stick out to the side so that no chicken gets behind you, but really one or two chickens behind you won't matter if the majority are ahead of you. As you stand there move slowly close enough so that, the chickens will naturally move away from you a bit toward the chicken house, slowly take a step so as not to frighten them but to put pressure on them to move again closer toward the gate. Tap the ground, saying "hut, hut" taking slow steps toward the gate as you move your presence will make the chickens just enough uncomfortable that they will move closer and closer to the gate, just keep moving keeping your arm stretched to the side tapping the ground near any stray chicken not headed in the right direction, but all chickens headed in the right direction do nothing to rush them.
The idea is you want the chickens to walk into the pen, once the first few walk in and find the treats the stragglers will come running, and if you make sure there is enough treats, that will keep them there, if you have to go back and get a straggler.
Mine know when I pick up the stick they are headed back into the run, and with in a very few moment I can get them all to walk right in. IF you RUSH this and they start to panic, they will scatter.
MrsK