In India sperm donation is governed by ART (Artificial Reproductive Techniques) act. For that you have to register with Sperm Bank or IVF clinic. After primary health check up and mandatory tests you can elgible for sperm donation. Now there is no live sperm donation, now freezing technique is used for all donated sperms.
On other note, you can also consider about blood donation and organ donation and make awareness about it.
Next Steps
Register with sperm bank/ IVF center.