gather your materials.
fabric: i used a 20X30 pillow case
tools: scissors, thread, sewing machine or needle, pins, iron
extras: ribbon for ties, or you can make your own out of left over fabric
Measure your kid, or their pants.
i tried to measure my son, not happening. i managed to measure his waist and then i had to use a pair of well fitting pants that were a good length.
you will want the waist measurement + about 5in.
the length measurment + 2 inches on top and bottom for hems. its good to err on the long side
the crotch measurment. i took his pants and just measured the crotch , it came out at about 16 in. or 11" tall and 2" deep.
my son is about 25lb and 30" tall his measurments were
waist: 20" ( so i measured 25" on the pillow case
length: 18" (i measured 20 " on the pillow case, to allow for seams )
crotch: 6" tall 2" deep ( i kept this measurment the same on the pillow case )
to make these pants you start with two squares of fabric, but since im using a pillow case, i didnt cut out two squares. i just left the pillow case whole untill i had sewn the crotch.
lay out your pillow case, mine was 20X30, so i cut off the extra 5"

fold your 25X20 fabric in half, and draw on your crotch like this

then draw a curve, and cut out

unfold your fabric and sew the u shaped crotch

now cut the top and bottom of the pillowcase

now you can hem or serge or topstitch the sides
so your pants should look like this right now...

basically you are looking at them sideways... pick them up like you were going to straddle the u shape and ride it like a horse.
the left and right sides of the u shape become the front and back of the crotch ( is this making sense ? )

see the seam of the crotch is now in the middle. you can now see where to add your ties... you need to add them to the front and back. or you could add some velcro.
now you can sew up your waist by folding down the top about an inch, or how ever big you want it. you can either add a drawstring now, or just tuck in some ties like i did

i took my pants and put them on my unwilling two year old, to see how long they needed to be, but if you know your measurments you can just go ahead and hem the bottoms as well.
the pants hanging up

the pants on an angry toddler

if you have questions ask. im not the best at making tutes, and i ramble so i dont even know if it makes sense now.
these are the two tutorials i looked at before i made the pants
http://laupre.wordpress.com/2008/06/29/easy-breezy-wrap-pants-tutorial/that one has better instructions than ive put togather.... so please look at it, its worth it.
i was still a bit confused untill i looked at this tute. its simpler and helped me visualize what i had to do to make them work.
http://community.livejournal.com/craftgrrl/10571744.html?style=minethey both have pictures demonstrating how to put the pants on
once you do it , its so easy.. it looks way more complicated than it is i promis.
these are the first pair of pants ive made since home ec in highschool. which was 8+ years ago. im a simple sewer, i never make anything that isnt made totally of straight lines, and i found these pants to be just my speed.
once you get it down, it could take 20 min or less to make.