Most packaged, small-volume tissue culture media are pre-measured to make 1000ml of medium when dissolved in water: packet of approximately 35g dissolved in 1000ml of water. If you buy some M&S as a ready-to-add-water packet (as in:
Murishage & Skoog premeasured ) then it comes with instructions. Basically you add the powdered media to a liter of water, mix to dissolve, then autoclave to sterilize. Avoid buying the M&S salts without sugar and agar in it, as that turns into more work than you need it to be.