If you need to file a Pennsylvania mechanics lien, this article should be helpful: How to File a Pennsylvania Mechanics Lien – Step by Step Guide to Get You Paid. Additionally, this page contains information that should be really useful: Pennsylvania Mechanics Lien Guide and FAQs. And, finally, note that Levelset can help with that, too: File a Lien | Levelset.
Finally, keep in mind that unless you were hired by the property owner, then a Notice of Intent to Lien will likely be required. You can learn all about that here: Pennsylvania Notice of Intent FAQs.