tl;dr Basically you just fill in the yellow boxes and it'll spit out a result.
Garbage in Garbage Out
Your results are only as good as your input data. This works best if all the data inputted is race level efforts that are relatively recent/representative of approximately your current fitness. If you're running Masters your 10k time from college won't be much use. That being said your fatigue factors shouldn't change dramatically over time so you should be ok with PRs that are a few years old (If anyone has any research on this please let me know)
The second page will ask you to input personal best across a number of distances. If you have longer races or race efforts at distances not listed feel free to add them and copy down the formulas. Short durations distort the model. I would suggest excluding your mile if it is faster than 6 minutes. If there are distances that you don't have data for be sure to delete the entire row otherwise you will get divide by zero errors and nothing will work.
The third page includes some helpful calculators. If you're missing either power or weight or distance (modeled metrics) it's possible to estimate them and that's included here. Again remember less precise inputs = less precise output. An interesting application here is that if you're new to power you can estimate power from old results as long as you know your weight. You can then set a power target for an upcoming race with more confidence.
The first page is your results. Enter a recent result that you want to use to predict your upcoming result. The known result must be shorter than the predicted result. It should be possible to do it the other way around as well but I'd have to adjust the equations and I've forgotten most of the Algebra I learned in High School so it's on the to-do list.
FTP @ TTE is a WKO4 metric. If you're not using WKO4 I'd recommend deleting that row rather than guessing at TTE. If you want to guess I'd say 50 minutes is a good starting point.
Precision is important. My mile time is listed at 1607m because that's the distance that WKO4 provided for that time. I know a mile is really 1609.34
It will calculate an RE fatigue factor but it does not use it. Rather it takes your power fatigue factor and uses that. It seems to work. Since there are so many factors included in RE I have to normalize for as many of them as possible to make the RE curve generalize. Your RE fatigue factor is listed on the second page at the bottom of the column if you want to try it.
For all the times I just said RE I meant ECOR. While the sheet provides RE all calculations are based on ECOR because that is what the formulas I was working from used.
If you're using WKO4 your RE there may differ from this if you used avg(speed) to calculate RE rather than distance/duration. Also if you don't have correct weights in WKO4.