Until now I've used custom channel for all my domain. But today I make an URL channel for webmaster-talk. If I want to create ads for content, in channel list I find only custom channel that I've created before. So, if I create an URL channel I must create also a custom channel with the same name? If I create a custom channel and an url channel, in the report page I find report about both. So, why to create an url channel if when I want to create an ad for content I don't find this channel in the channels list?

I hope you understand what I mean, I still improve my english

For example, you will understand easily.
I set up custom channels for my adulu.com(forum), Adulu directory, Adulu exchange. we can know how much money i made from each custom channel.
for example I have 4 channel and each channel earning $1, Total is $4
also those channel all are from www.adulu.com domain name.

therefore we can know URL channel = $4(from www.adulu.com domain name of channels)


snapshot from instance
URL =0.23 is from custom's total

URL channels are useful because they don't require tweaking your ad code to get them to work.

For example, you want to monitor pageA performance, but don't want to create custom ad code for it (if your ad codes are all in one server-side include) - you can just create it in AdSense admin without doing anything on your site's side.