Welcome! I asume you have the impeller/pump that mounts to front of engine? No worries, I went thru the same thing awhile back and posted about it here
http://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=9886The thing to remember is to take your time and you should have it done in under 30 min. The only tools you should need are a 9/16 wrench, large flat blade screwdriver and a little muscle.
Remove hoses from back of pump (lower left side of engine as you are looking at it).
Loosen 2 bolts from bracket.
Remove fanbelt.
Remove bolts and pump.
Remove screws from back of pump and remove cover.
Remove old impeller (might have to really work it out depending how worn it is). Try to be careful and not gouge inside of pump.
Clean thoroughly, looking for any pieces of old impeller.
Reinstall new impeller (you do have the kit right?) using all the glycerine that comes with it, ya gotta really lube that sucker up.
Install gasket, then backplate, then reverse the un-install process for the pump.
Hook up the muffs, let er run for a bit to check everything is good....happy boating!