Grammar help please?

Hi there,

Could you advise me which word is the best for these sentences, please?

I constrained / restrained my dog at home.

I was constrained / restrained at room by my mum.

The police constrained / restrained the thief.

I wonder, if I used this word "spirit" properly and correctly?

He leaded people through the war or the fight, since that he has been a leader of the spirit in that country.

The spirit of a law is more important then it’s word.

I am in a low spirit. (Means I don’t have any energy, either physically or mind)

Thanks in advance.