Your best bet is to replace the whole tank instead of fixing it. You could try resealing it, but most of the time that is only a temporary fix. I would advise if you are going to fix it you clean the area really well and use a 2 part epoxy. If you decide to replace it here is how. I hope this helps!
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten Tighten the washer solvent container screw to 3 N·m (27 lb in).
Tighten Tighten the air induction assembly screws to 10 N·m (88 lb in).
Tighten Tighten the top forward screw to 10 N·m (88 lb in).