I have lipedema, rather than lymphedema but I dry brush every day. It is actually wonderfully good for your whole system and feels great. You must use a natural bristle brush that is specifically for the purpose (they are not expensive) and use light strokes. It may help your lymphedema, and it will do no harm,as long as you don't scrub at your skin.
The weird thing about it is that I had an effect that I simply wasn't expecting. I have very mild psoriasis on my elbows. At one stage i had run out of my cream, and it was acting up and was looking pretty red and angry. I started dry-brushing, avoiding the area, and within a week the psoriasis had pretty much abated. Very strange. I have stopped and started it to see if it was just a one off thing, but no......if I don't dry brush, the psoriasis gets worse.
Anyway, there are many videos on youtube showing demonstrations of the technique. Here is a website that also describes the technique in detail.
i hope this helps