osm offline map

i want get a web app
and use osm offline map
Cani get it?
how to download osm offline map?

It is not entirely clear what you want to achieve. Do you want a smartphone app? Or a website you can use on your computer without internet? Or a tool to see the map (which doesn’t have to be in-browser). Do you just want to see the map or do you want to be able to do something with it (navigate, lay-out,…).

If you clarify these questions, you’re more likely to get an answer on http://help.openstreetmap.org

This is a nice starting page to learn about all kinds of applications that use OSM.