how to join bars in dorico

please tell me how to join bars in dorico. thanks!

Engraving options (cmd-shift-E), barlines, barlines joins.
Hope it helps !

It did not work. maybe I do not succeed to select two bar for joining

You do not have to select any barline. It is an option that should work for the entire project !
Maybe if you could upload a png file (no need to zip it) it could be clearer what your problem is, and bring you an appropriate solution :wink:

First of all my problem is I don"t know to select a bar. illustrates my picture a selected bar? thanks!

Clicking within the barlines [Edit: Stafflines], but not on notes and rests, will select everything in that bar. Ctrl-click to add other bars to the selection. Not sure what you imply by joining bars, but perhaps you need to e.g. make two 4/4 bars into one 8/4 bar? In that case you could delete the barline and reapply time signatures…