Ok here is a guide with my bad english.
What are blobs for?
When Apple release a new FW for a product, they stop signing old fw, which means that you cannot downgrade via the apple way.
How do i save my blobs
First download Tinyumbrella and install it.
Second plug your IOS device in the USB with the Apple Cable
Third Click on your device in Tinyumbrella then click Advance tab
4th Make sure Request SHSH from Cydia is uncheck then click Apply Changes
5th Go back the the main page then click Save SHSH You should see in the middle box your machine with the version like this as an exemple
[url=http://img807.imageshack.us/img807/7982/capturedcran20110705080.png]Image[/URL]
Then your SHSH is saved
Now how to restore.
First make sure that if you go in System Preferences then sharing that Web Sharing is deactivated this will give you error Kill HTTPD on Tinyumbrella opening.
Then click Start TSS server in TinyUmbrella
Then open terminal and ping gs.apple.com it should respond by 127.0.0.1
Then Go and download the original FW for your device exemple Ipad2 4.3.3
Open itunes with your Ios machine pluged in and instead of clicking restore
Hold Alt(Option) then click restore and then manually go select the original firmware you just dowloaded.
When it<s done. Let the work do the rest, then restore the backup from Itunes to get your apps back
Thats about it