hi how can I file a lean. we have been waiting a few months without payments
If you did not serve a preliminary notice and the work was done months ago, you cannot file a lien. Please hire a construction attorney to provide you the preliminary notice and lien form to use going forward. You must properly serve the preliminary within 20 days of starting work. Always do this and do it properly, which is why you need an attorney. They will also advise on your contract and you need that as well.
You can sue, hope to win, and then hope to collect.