It is difficult to answer your question without knowing more about your situation, especially the relationship between you and your baby's father. Certainly you are right in wanting your son to know—and be loved by—his father. But that is something that is difficult to force. I have a few suggestions. First, if possible, I would contact his parents (or one of them). If they live near you, go see them and take your baby with you. After all, he is their grandson, and a grandparent's love is very powerful. Second, I urge you to have a paternity test done. This can now be done with a drop of saliva and does not require drawing blood. Having definitely established paternity may be very important to you in later years. Talk to a lawyer about this.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.