First make some media. Use whatever you can find. Some people just use malt extract. You can go to your local homebrew store to get media for a starter. I make my own use 3g malt extract, 10g dextrose, 3g yeast extract, 5g peptone in 1 Liter of water.
Put the media into jars. Since you want to make starters I am assuming you want to have enough yeast to pitch directly from these. You will need to calculate the amount of cells needed to pitch. Use Mr. Malty's Pitching Rate Calculator. The problem with the calculator is that it takes it assumes manufactured liquid or dry yeast or from a slurry. You have none of these so you will have to be creative to estimate the number of cells. You need "about 1.5 million for a lager and 0.75 million for an ale." If you want to get technical you can try to do a Yeast Plate Count, but that might be more work that you want to do. If you want to try you can PM me and I will go more into depth on how to do. I was going to write up a guide in the wiki so you could give me the jump start to do so.
Now sterilize the media that is in the jars. If you have access to an autoclave (you or a friend has access to a lab) then use that, if not go with a pressure cooker or just put the jars in a covered pot of a small amount of boiling water. Keep the lids slightly open, you dont want the pressure to crush the jars. If boiling do for 1 hour. Let the jars cooll down. Then using aseptic technique add the yeast. For you I would take your pack of dried yeas and wipe around the entire surface of the pack, keep your surface area clean and disinfected with bleach, and if you have them put on gloves. Now open your pack and sprinkle a little into you jars/flasks/ect and cover with sterilized foil (sterilize the foil with the media).
Let them grow for about 3 days and shake 3 to 4 times a day if you can. Then when you are ready then pitch. Like I said earlier, it is hard to make sure you are pitching the correct amount of yeast without a real measurement. If you are using US-05 it gets to about 200 billion cells in 1.5 L of my media in 2 days. Every yeast has a different growth rate based on the temperature, media, and other variables.
If you want consistent efficient results then buy 6 dry yeast packs. But if you want to have fun then culture your own yeasts. If you have any questions just send me a PM.