Welcome to PA. I assume you are from Germany. Quite a few of our German friends here on Pa and maybe some close to where you live.
"The Bent Stick" by Paul Comstock is a very good beginners book and especially if you don't have access to osage or yew. George Tsoukalas' site here on PA(look at the top of the "How To" thread) will give you all the info you will need to build a bow , arrows and other necessities, from locally obtainable materials; both store bought or found.
The Traditional Bowyers Bible, Vols I, II, III and IV are all worth their cost in info.
"Bows From Boards", by Vaughn Ditto and "The Flat Bow" by hunt & Metz, both have good bow building info.