Purchase a professional-quality snake trap. A trap is the best way to catch a snake without endangering either yourself or the animal. Once the snake is in the trap, it will be safe but immobilized.
Place the trap in a corner of the garden closest to where you last saw the snake or snakes. Set the trap according to the instructions that came with it.
Check the trap each day to see if you have captured your garden snake. Contact animal control if you even suspect that the snake in your trap may be poisonous. If you are absolutely certain you are dealing with a non-venomous snake, you can relocate it to a spot on your property well away from your garden.