instructions a manual.
you basically disconnect the shift shaft under the carb, remove the lower unit mounting bolts, there is one that hides under the trim tab. drop the lower, and 4 screws on the water pump. be sure to replace all rubber, order a kit, not just the impeller.
Other things to mention, you will need a can of gasket sealing compound. I use BRP's brand with the built in brush in the lid. A tube of marine grease for the drive shaft splines (and prop shaft splines, I remove my prop when I drop my lower unit to ensure I do not damage it, as well as to grease the splines and remove any fishing line from the prop shaft.)