How would I figure out my cycling Power/Watts in excel

OK friends I am looking for big help here.
First off I am a cyclist, riding is a way of life for me and in fact long story short about 5 months ago my car finally died and I am done with the hole car payments/insurance/maintenance/gas thing and I am jist starting to see the savings now.So which ever way you stand on the "gobal warming" and "Debt" issue this country has USA, I just killed 2 birds with 1 stone. So I bought a really nice bike and the bike comoiters Garmin edge 1000 along with database softwares to log my rides and data. But I would love to figure out my riding (power/watts) but have NO idea how to go about this or what formulas excel would need to useand or data from my rides to input like rider weight, time riding, Cadence, heart rate, wind speed, temperature outside etc.. Or how excel should be laided out.
I know excel could do something this easy but I don't know how or where to begin, so I am asking for big help.
Thank you,
Brian

Thank you as I already know this, I want to be able to do it in excel and I believe it can be done. Also I am not inputting my personal data on website that can do the calculations for me as I know of the massive data mining they do on these tyoe of websites. So I would prefer to do it locally on my Computer

There is a formula one of my friends sent me as well as a video link on youtube where this doctor figured out how to do it. I will post ot tonight when I get home. I am trying to do this formula in excel but I am not that good with it.

I think you are getting to specific. I am just looking for general power/watt calculations but thank you for your input