Before you can use the radar dish, your Engineer has to reprogram it using the nearby control tower. Move an Engineer near the control tower, and the Engineer will reprogram the radar dish automatically.
Once the radar dish is under your control, select it by clicking on it. The camera should switch to the radar dish. Move so that you are pointing at the destination radar dish and click on it. A communication tunnel will open between the radar dishes. Deselect the radar dish with the tab key and then select your Squad by clicking on it. Once the Squad has been selected, click on the radar dish, and they will move to the dish and be transported.