Hello,
Thanks a lot for your answers.I can now to work in omnitik.Now ,I want to know if possible to use mikrotik sxt U- 5HnD as a bridge and 2 Mikrotik U-5HD as station .What is the difference between SXT can work sa bridge and station and SXT can work only as a station? 
Dear,
It is easy. first use MK PoE and power OmniTik via its Ethernet 1. Then connect your computer and using Winbox choose the Access Point Bridge wireless Mode (choose SSID, Frecuency, Protocol, etc). in SXT device you must do the same but the difference is that you must choose a client mode (Station when using routing or sation bridge if you are working in layer 2). The client mode must follow access point parameters.
When you turn it on, it will already work as an AP. For basic operation, no configuration is needed.