My kids and I took off an afternoon to work on a wikkiup in a place that we have thought would be good to do it. We picked a spot right on a creek where there is a natural spring and we've been to the spot enough to know it doesn't flood at any time of the year.
Right near this spot are old broken cottonwoods which tend to break off in large splinters that leave huge slabs of material to use as shingles. There are also some green alders that were washed away at the bank and were blocking the creek somewhat. Alder, no matter if it's green or dry is very brittle and pretty large trunks can be broken off.
The point of this exercise is to show my kids that good dwellings can be made with what is available. When it's done is should be fairly rain proof and tall enough to have a fire inside. Right now it's drying a bit as it is very heavy from being green and the large slabs are still wet with the rain we've been having.
In the above picture you can see how we used the natural forks of the trees to make an interlocking center. You can make the center interlock very tightly by laying everything down on the ground first and interlocking it while it's on the ground. Then you raise it up in the middle and keep pushing it up. The increasing angle will really help bind the forks together.
The above shows the large slabs of cottonwood that will overlap as shingles.
This last pic shows the approximate size of the shelter. I can easily stand up and have room to reach up still in the center. It should sleep 4 pretty comfortably.