Welcome from me as well. Great advice from Tom. As he says, softer reeds help the lower notes (but they make the higher ones sound terrible if they're too soft). Depending on your mouthpiece, at first you may need to go even softer than Tom suggests. Apart from breath support, a relaxed embouchure is also needed - many people start off too tight.
If you start playing down the scale, and a particularl note (often C ) stops dead it's often because of lack of breath suport.
Take your time and work down gradually. One of the first things I was taught is that low notes are hard on a sax and easy on a clarinet, where you struggle with the higher ones. And start early learning to breath with your diaphragm/belly muscles where the support comes from, not ribs.
