You are not required to retain an attorney to assist you about the matters you have written about in your question, however having one would probably make the process go much smoother to resolution.To find a form for filing a lawsuit presumably you can go online to find such or if the amount of your claimed damages is not significant and would fall within small claims court jurisdiction, you can go down to your county court house to get a small claims court complaint.Another option would be to go to your county law library and ask the law librarian for the forms to file the lawsuit you want to file. I suggest that before you file you send a written demand letter to the commercial tenant keeping a copy for future need and use.