After GRE exam you can send the score to 4 universities for free.
For the computer-delivered GRE® General Test, you will be asked to designate your free score recipients at the test center.
For the paper-delivered GRE General Test, you will be asked to designate your free score recipients during registration.
After that, you send score by paying a fee to ETS and send the score via them. For details check ETS website https://www.ets.org/gre/revised_general/scores/send/asr