One way is to start the seeds between two pieces of paper or a towel soaked with water. The towel is kept moist each day. Germinating some types of seeds is more complicated than just soaking in water. Some seeds need to be damaged in some way to germinate, and others are specialized to respond to periods of temperature or light. If there something you would like to grow, it might help to learn what the seed requirements are to germinate.
Some plants can reproduce from cuttings.
This means cutting a small part of the growing tip of a plant, pulling off the bottom leaves and sticking the cut end into the growing media. Some of the plants that can be reproduced from cuttings are basils and many of the herbs. Garlic reproduces from individual garlic cloves. Some of the garlic in the grocery store is treated and will not sprout. An organic garlic is more likely to sprout.