how to finish to change my changes?

It's a bit difficult to know what the problem is that you're having. Could you perhaps describe it in a little more detail?

Maybe you're editing using the online editor and want to know how to save your edits? Maybe you're drawing a way as described here and want to know how to stop when you've got to the end?

From looking at this cycleway here I suspect that it's the latter - and the answer is once you've clicked on the endpoint of the way (in the case of that cycleway it was the road to the left) just press return - that will stop drawing the way.

There are some handy videos that you might find useful here, and if you haven't already read it, the main "beginners' guide" is here.