There are two kinds of forearm training movements. One is the reverse wrist grip and the other is the forward wrist grip. Look at the picture below.
You'd better find a barbell to do these two movements. For dumbbells, because the wrist angle is too flexible, the training action can not be as stable as that with barbells, so the training effect is not as ideal as barbells. The action of biceps brachii is very simple. Basically, you can practice it by doing two actions: bending your arm and bending your hammer.
After the action, let's talk about how to practice. These four movements constitute a training content. You should practice these four movements three times a week and once every other day. During training, you do 4 groups of each movement, and each group does 12. Rest for 30 seconds between groups. Weight during training You should find a weight that you will be exhausted after doing 12 times. Maybe your dumbbells are not heavy enough, so you need to buy dumbbell pieces again. The practice of light weight and many repetitions is basically ineffective. So make sure the weight is right. At least 1 interchangeable dumbbell with counterweight of 40kg.
The muscles of the upper limbs, the muscles of the chest, including the muscles of the shoulders, and most of the muscles of the back can basically be trained into dumbbells. Although it is not omnipotent, most muscle groups can be trained into dumbbells.