I have a pocket obd2 it says my 1999 infiniti g20 has a p0446 problem

SOURCE: location of flasher for my 1993 infiniti g20

what is it that you have to change your flasher? have you check the fuses that may fix your problem. now your flasher location is under your sterring colum by the fuse box

SOURCE: infinity g20

This is a big job and the procedures required for removal and installation are too large for this post. But...what you can do is, go to the local Library and sign out a manual and review what procedures need to be done. This will give you a good idea of other procedures as well.