You have to set up the folders correctly and sign all your apk's and then remember to sign the final zip. -do this by right clicking and click open with java. To see where everything goes just take a rom zip and open it and start clicking around. The android central froyo rom has the battery percent and all that included in the update. I just don't like it because it's like watching the clock at work. I don't need to pay that much attention to my battery.
Oh and don't save your png as interlaced and you have to make sure it asks if you want to overwrite the existing file. you don't want duplicates. also, make sure there is nothing extra in the file like a res folder or anything like that.