AS my screen indicates I'm a rookie. In trying to remove my bathroom sink the metal piping melted in my hand from hard water silt. I'm trying to replace the piping and was told that I could connect new plastic piping to the metal piping coming from the wall. The wall pipe does not have threads and I attempted to attach a thread adapter and could not get a tight seal. I'm have a p-trap kit, extension piping, primer, cement, teflon thread sealant, joint compound....just don't know how to use them correctly. Thanks for any help you can give. The rookie!!