I came across this phrase: "I will go to the wall for them"...
Does it mean that this person is going to do what is necessary for them or does it mean something else????

(English is not my first language):-(

Yes! Good guess :)

From http://www.thefreedictionary.com/

go to the wall Informal
1. To lose a conflict or be defeated; yield: Despite their efforts, the team went to the wall.
2. To be forced into bankruptcy; fail.
3. To make an all-out effort, especially in defending another.

Thanks!!!!!!

(Why didn't I know that site????? I really wonder)...

In my context it is the third definition!!!

Thanks again!

Don't beat yourself up. I didn't know the website either, I just did some searching.