To add You Tube Button to your blog just follow the simple steps.
1) Go to the website Click the Link given below
https://developers.google.com/youtube/youtube_subscribe_button
now you have to copy your YouTube channel ID and paste it to Channel Name or ID
2) Now copy the code which is generated for your blog and paste it to Your Blog
Setting are as
go to Layout-> Add gadget-> HTML&Java click + and paste the code here
now save.view or refresh the blog to check the updates