When you’re ready to start the seeds, just add water. The moisture softens the coating of the seed and allows the internal food source to start feeding the seedling.
A very important point to keep note of is that the seed medium must stay moist at all times but not soggy. If it gets too soggy, the roots and seed will rot and/or grow mold. However, if it gets too dry, the roots will dry out and die.
Most garden centers sell Seed Raising Mix, which is usually a mix of compost, soil and sand. This is much easier to grow seeds in as it holds moisture much better.