Hi every one ,, i have 2 IP from 2 ISP
i want put one of it Backup
i want put the 2 ISP in on RB1100 and and put the 1 ISP master and the 2 ISP like backup
when the first down the second will work automatic without any problems
any one can give me best idea about this
thnaks

The best idea is to read some of the threads about this topic here on the forum. Search for failover. Your question is already answered many times.

In ip -> route, your must have as you default gateway, your main ISP with distance=1 and the backup ISP with distance=2.
This will do what you want...

I wrote it many times. It is not enough. Search for threads where it is discussed.