At the least, you should attach to the informal brief the district court docket entries, the complaint or pleadings, the order of the district court, the district court opinion, if any, and the notice of appeal. You should also include any parts of the record deemed relevant or important. In choosing which parts of the record to include, keep in mind that the entire district court record is available to this court for review. Only documents that were filed in the district court may be included; new material may not be included in the appendix.
If you choose to file a formal brief, you must file a formal appendix that complies with FRAP 30 and 3rd Cir. LAR 28, 32.
You may file a motion to proceed on the original record which, if granted, would dispense with the requirements of filing an appendix or attaching certain documents to the informal brief. FRAP 30(f); 3rd Cir. LAR 30.2. However, if the motion is granted, you still must attach to each copy of your brief a copy of the docket entries in the proceedings below; a copy of the notice of appeal; and a copy of the order(s) appealed and any opinion or decision of the trial court or agency. FRAP 30; 3rd Cir. LAR 28.1, 30.2. In cases involving petitions for a writ of habeas corpus (28 U.S.C. §§ 2241, 2254 or 2255) or when leave has been granted for the appellant to proceed in forma pauperis, the appeal will be heard on the original record. 3rd Cir. LAR 30.2.