I had the same issue,
for anyone else that ends up encountering this issue and is new to git, assembla, netbeans here is a slightly more elaborated guide.
Create a local repository as instructed by assembla, then push the repository. All this can be done on the msysgit client command line.
First things first, create an ssh key by entering :
ssh-keygen -t rsa
Do not enter a name for the key, just press enter. You do not need to create the password either.
Once the keys are created, upload the id_rsa.pub key to assembla. (generally found in username/.ssh/ directory on a windows machine. eg C:\Users\username\.ssh\id_rsa.pub)
In all, the following instructions need to get executed :
git config --global user.name "your name" # Set your name
git config --global user.email "your@email" # Set an email
Setting the email is important because assembla checks for it. Be sure to provide the one that you registered with.
mkdir myproject
cd myproject
git init
touch README
git add README
git commit -m "first commit"
git remote add origin git@git.assembla.com:myproject.git
git push origin master
After Initializing Git in netbeans To clone a repository in Netbeans, the following options get me through:
Repository URL : git.assembla.com:myproject.git
Username : git
Private Key File : C:\Users\username\\.ssh\id_rsa
Hope this helps people like me who are just starting out.