Sending GPX.file from garmin connect to my forerunner 945

Import it as a cycling course to Garmin Connect, and then use the button Send to Device from Garmin Connect.

sure

and now it is too late to modify the screen to put cyclisme instead of course virtuelle by guebwiller velo datas

If you want to change an activity's type - open selected activity as full page. Then you can choose from all types.

On activities' list, as screenshot shows, you can only switch sub-types.

you have more choices but not the good one

cyclisme or bicycle is still missing in this menu

thank you i find it

Well, the original question was why you see the Course under Running and not under Cycling. That would avoid the necessity to use the Running profile for the Course, and having to to change the activity type each time in Garmin Connect later. In case I did not write it comprehensively enough, in my first reply, I attach some screenshots showing how to do it, step by step.

1. Take your GPX file, and import it on the page Training » Courses
   
   
   
   
2. When you upload your GPX file, Garmin Connect will ask you to select the type of the Course, so select the type you want to use for it (i.e. Road Cycling):
   
   
   
   
3. Once you adjust the title and save the course, click the button Send to Device, to upload it to your watch: