I want to create gps tracer with my smartphone

If you are writing this app as a learning exercise, go for it. If not, consider first trying some of the existing apps, and you can use the time you save to create something new and innovative.

On an iPhone, I use OSMTrack by Dmitri Toropov, which works brilliantly and is well worth the $2 or so that (I vaguely remember) it cost.

On Android, I use OSMTracker by Nicolas Guillaumin, which is free, and almost as brilliant.

Good luck either way.

p.s. should "disponibility" be "responsibility"?

Firstly, you say that you're writing a "GPS tracer" and "need some help to know how to start if I need to update the map". You've probably already read the various Beginners' Guide pages. Applications that talk to OSM directly to upload data (such as uploading GPS traces) might do so using Oauth.

You then say "if I need to update the map to host my own copy to guarantee full availability". Does this mean that you want to render OSM data on some sort of map on the phone? If so there are essentially two choices - vector rendering or some sort of map tiles. If you're thinking of using tiles, have a read of the relevant switch2osm section for more information. If vector rendering, depending on the platform there may be something that you can build upon.

If you think that you'll be making a lot of calls to OSM's APIs, then have a read of the API usage policy. If you're planning to access OSM tiles directly, read the tile usage policy.

The "dev" mailing list might also be looking at (it's archives are searchable) and there's also IRC - the #osm, #osm-dev channel might be useful, and there are also many non-English-language OSM IRC channels.

However, I'm not entirely sure what you're asking for help about here - so apologies if I've not understood what you've asked. I'm guessing that English isn't your first language - perhaps it might help to ask in that language? Lots of people here don't speak English as a first language and may be able to help directly.