Go see a licensed massage therapist first. They are really not that much where I am, around $25 per session, and even if you just went one time, I'm sure you could learn a lot.
As far as I know, knots are just your muscles contracting and not releasing. Mine usually will do this from overwork/pain.
Just for at-home help, take a nice hot shower, then get a helper to gently rub in some good old fashioned rubbing alcohol...not too aggressively, just enough to get it where it needs to go. It's stinky, but the fumes will clear up in a few minutes, and it's worth it. I usually take it with about 4 extra strength tylenol, and in about half an hour, even from being in crying pain, this loosens things up (alcohol) and blocks the pain (tylenol).
If I've overdone it physically and know I'm going to be sore/knotted up, I put some rubbing alcohol on before bed and skip the tylenol...this just keeps things from locking up overnight. If you don't have a helper, you can just pour the RA over your back in the shower, leave it for a minute or two to soak in, then continue with your shower as usual...turn the fan on, though, so the fumes don't get to you.
Just as a side note, RA works great on swollen, fluid-filled ankles...just rub it in morning or night...it really works!
I am not a doctor, nor do I play one on TV, so this is just my personal experience and opinion.