Question
Can you give me guidance on building tree house or can you direct me to a source. thanks

Answer
Such a simple-sounding question....but, WOW!  what a full subject!  There are books, seminars, and court cases over this simple, humble structure.  I've made a few in the places I've called "Home".  They're not complicated affairs - unless your neighbor, mayor, or local building official disagree with you.

Here are some quick sources for some ideas & books:

http://www.treehouseworkshop.com/
http://www.stilesdesigns.com/treehouses1.html

I think I've even seen a design book on the local Lowes/Home Depot shelf.  You can also type in "treehouse" in the google search engine, and fill your computer with all sorts of great ideas.

And now the uglier side - the story of one determined family in Missippi:

http://www.saveourtreehouse.com

And, sadly, I have heard of other such cases. This is law that is being written, as we speak.  Namely, do I have the right to create a structure where there once was none?  Do I need the government's permission through permits?  If so, Why?  Even if there are no "utilities" to it, or it is not used for "habitation"?

Of course, if you're out in the countryside, nobody will mind.  But if you live in a big city like L.A., then official permits may be required, with framing inspections & everything!  Especially if the views from there are fantastic - if you can see out, others can see you up there, and might not like your new playspace overlooking their backyard or second-story bedroom.  

Hope I've not scared you away form creating a fun & enjoyable landscape feature for the whole family...It really is worth the effort.  My kids loved there's in the Virginia forest.

-Marc