If you are new to dressage, what you might want to practise is just first following the horse's mouth so that you get really good at feeling where the mouth is and having a steady hand. This is really, really valuable and takes time to achieve.
Once you can truly follow a horse's mouth, then you will be able to ask it to give to the bit a little and have a little arch to the neck. THis is NOT collection and is not something you do and think you have now done dressage., But it's ok to feel the difference between following the horse, thus not affecting it throught the rein, and using your hands/reins to ask it to put it's head somewhere, or for it to listen to your hands via the bit.
It then becomes a dialogue , you listening (following passively) and you talking (making your hands a bit firmer and asking the hrose to lift it's head and flex for a moment in the jaw). NOT collection, but a good thing to experiement with to develop your ability to speak to the horse via the reins.