Git+ssh, which config file should I use for ssh settings?

Good morning,
I set up a repo as follows:

git remote add origin git@git.assembla.com:mconverter.git

But, I can't push to it by using the command below:

git push origin master

I get:

ssh:fatal: The remote end hung up unexpectedly

If I run Git-Gui I push, I get:
ssh: connect to host git.assembla.com port 22: Bad file number
Pushing to git@git.assembla.com:mconverter.git
fatal: The remote end hung up unexpectedly

What am I doing wrong, and how did git know that I using git+ssh? I
installed Git on windows Vista, the SSH that comes with git is inside
the git program folder under 'bin'. So where do I place the config
files? My git folder is C:\Program Files\Git\, and ssh is in
C:\Program Files\Git\bin. Do I need to create etc folder under git and
name it as ssh_config for the ssh options? My ISP blocks all ports
except 443/80. I am trying to set up a tunnel to push git through.
Please help!
Ravi.