Help using a resin cleaner in water softener

I am not familiar with water softeners at all so I hope some one can help me. We purchased a house with a Kenmore water softener installed already. We were told that it worked when they last used it (older lady moved into a nursing home and it hadn't been ran for about 2 yrs). We had to empty out all the salt that was inside - rock solid and dead mice in there.... yes, I said mice! They were dead all over the place (whole other story).

Anyway my husband dumped everything out and cleaned it very well. When we were getting all the salt out we lost some of that resin stuff as well. We hooked it back up, called Sears and had them send out someone to run a maintenance check on it - that was a COMPLETE joke. He cleaned some filters and then made sure it would go through all the cycles - I don't think he even did all that. He said everything was working properly. I brought a sample into Sears and they said it was working and all should be good as well.

But here is my problem...our old place had a softener and our water was much softer there - a lot softer actually. I increased the hardness level a couple of times and did a regenerate and not a lot seems to have changed. We have rural water that has a bit of iron in it. We use the Morton salt pellets. And we have MAJOR water spots on all of are faucets and sinks.

Wondering about using a Resin Cleaner - hubby bought some jug at Menards. And we also got some new resin to add to the softener because we figured that must be low now that we lost some in the cleaning.

I haven't used the cleaner yet or added the resin because I am a little unclear on where to actually add the cleaner in the softener and feel that I don't want to add fresh resin until I probably clean it.

Sorry this got so long but I want to cover all my bases in hopes that I don't have a dozen questions, but a dozen answers. Thanks for any and all your help.

Tanya