If the controller is damaged (assuming that possibility), how can I know this?

At this point, as long as you have not done anything you haven't told us, your data is probably just fine.

RAID Overview

A RAID 5 stripes your data across all 8 physical disks. Along with that data, it writes "parity" data across the disks with the actual data so that if one disk ever goes missing, it can use the data and parity to calculate what data is on the missing disk.  This means that in a RAID 5, you can lose ONE disk and still have your data be accessible.  If you lose more than one disk, then your array is OFFLINE, because it no longer has enough data to calculate what is missing.  The RAID configuration is stored on both the controller and the individual disks, so if ever the configuration on a disk differs from what the controller has, that disk is marked as FOREIGN ... and it stays foreign until you tell the controller what to do with it.  

In your case, you need to import the data, which will bring at least one of the two foreign disks online, making your data accessible again (so long as faulty drives or corrupt RAID configurations do not prevent such a course of action from completing successfully).  The two most common reasons for a disk (or multiple disks) to get flagged as foreign it a faulty disk(s) or out of date firmware.

I ask this because I have read some info in the internet, I havent touched anything, and the server is properly protected with UPS.

But my information could be safe? sorry but i dont understand very well how this technology works, the disks that are foreign are the disk 0 (witch is the first one) and disk 8 , there are more important for the array or all the disk has the same priority?

My main fear is not to be able to recover my data, so I really want to avoid doing things that can harm permanetly my information, in this case losing all for trying to import a foreing configuration in a damaged controller , I know that are thousands of scenarios but according you expertice (that looks excellent :)) do yo think is safe doing this?

"If the controller is damaged (assuming that possibility), how can I know this?"

You can try to run diagnostics on the controller (bootable 32-bit Diagnostics), or you can replace the controller to test.  Although a faulty controller is a possibility, it is FAR LESS LIKELY the cause, and FAR MORE LIKELY caused by a bad physical disk or out of date firmware.

"I ask this because I have read some info in the internet"

This is dangerous, but what have you read (so I can set the record straight)?

The only way to try to get this back up and running is to IMPORT the Foreign Configuration.  There is a good chance that only one will come back online, so import it, then attempt to boot.  If you can boot, then you will need to test your drives to make sure all are healthy, replacing any that are not, then update all your system firmware (BIOS, ESM, PERC (driver first), and HDD).

Degraded, sorry

ONLINE = array is online and all disks are online

DEGRADED = array is online, but one disk in RAID 5 is failed (or foreign or missing)

FAILED = array is offline, two or more disks are failed (or foreign or missing)

What OS are you running? Does it boot?

Which disk is currently still missing?  Is it showing as FAILED now?