TSS is training load for one ride. ATL is a weekly rolling sum of TSS. CTL is a 6 week rolling sum of ATL. TSB is the difference between CTL and ATL.
From what I understand, I basically should try increasing my ATL by say 5% a week for 4-6 weeks, then back off for a week to recover/peak. Then start all over again, but with a higher initial ATL (if the previoius block went well), go for 4-6 weeks, then back off to again recover/peak. The goal is to drive your CTL as high as possible without overtraining, then when you drop your ATL, your TSB will spike.
In other words, train hard, take a rest week, then race. The CTL is basically quantifying how hard you trained [over the training block], your ATL is how much you are [currently] resting [or training], and your TSB predicts how in shape you are going to be, at least compared to yourself in other instances.
I know there are many smaller caveats in there, but that is the general theory right?