Hi all i am not getting understand what is actual concept of propeller for pulling the air plane or to generate thrust

i gon through web but still

please 

Alright! Compare an ordinary threaded screw to an propeller. Screw has threads while propeller has its blades angled at some degrees. These blades works same as these threads in screw as both pull or push the themselves ahead or backward through the surrounding depending on the rotation. Screw comes out when screwed in Anticlockwise direction and goes in when screwed in clockwise direction. Similarly, the propeller does same but through the air. That is why it is also known as Air-screw. Each propeller has some pitch (which is how much inch propeller passes through air in one complete rotation). More the degrees the blades are angled at, More will be the pitch, thus more distance it will cover in one rotation and therefore more the pitch speed for a given RPM.

Refer below image, so you don't get confused in what the "degrees" I have stated for...




Hope you got everything in above explanation.
Thanks.

ok thanks for that

one more 

how to decide propeller size if i have

motor configuration

air plane configuration

http://www.rcindia.org/rc-general-topics/working-of-motors-what-is-the-significance-of-kv-to-prop-size/

http://www.rcindia.org/electric-power/understanding-electric-power-systems/

http://www.rcindia.org/beginners-zone/selection-of-power-system-and-components/

These are the readings I suggest.

And yes! you should also try to search forum about your questions by using search box in right above. Many questions are repeatedly asked again & again but for what...Same answer every time. I hope you understand.

Thanks.

yes sir

    

Don't call me Sir! I am younger than you.