Step 1: As a first step, you need to download RedSnow version 0.9.9b7, either for Windows or Mac as it allows you to save SHSH blobs.
RedSnow - Windows
RedSnow - Mac
Step 2: Once RedSnow is downloaded, launch it by double clicking on it. On the RedSnow application main screen, you will find two buttons -- Jailbreak and Extras. If you are looking for how to jailbreak your iPhone with iOS 5, you can read the tutorial here.
Click the Extras button to continue. On the next screen, you will find a couple of buttons namely -- Fetch, Verify, Submit, Query and Stitch.
Fetch: If you are saving the iPhone blobs for the first time, you will be clicking on this button. This will grab the SHSH blobs from your iPhone and save them directly on the Cydia server.
Verify: Click this button to make sure that the blob you are going to save on the Cydia server is correct.
Submit: If you have already saved your iPhone’s SHSH blobs on your computer, you can click the Submit button and select the required file. Once done, RedSnow will upload the SHSH blobs to the Cydia server.
Query: This button will allow you to see all the available blobs for your iPhone that you saved on the Cydia servers. You will get a popup window when you press this button. Type *(finds all available blobs for your iPhone) and click ok.
Stitch: This is used to personalize an ipsw with the blob. You can also stitch a blob to the ipsw file.
Step 3: Click the Fetch button and RedSnow will now ask you to put your iPhone in DFU mode. Once your iPhone is in DFU mode, it will start fetching the blobs from your iPhone and submit them to the Cydia servers. The progress will be visible in the RedSnow application window.
Once completed successfully, you will see a success message.
Step 4: Now, the next step is to make sure that your iPhone blobs have been saved on the Cydia servers. To verify the blobs, click on the Query button to continue. In the popup window that appears, type * and press the Ok button. * is used to get all the blobs available on the Cydia servers for your iPhone.
You will now see a list of available blobs for your iPhone.
For added safety, RedSnow saves a copy of your iPhone’s SHSH blobs in a “plist" file located within the RedSnow folder.
Note: You can also use TinyUmbrella to locally save SHSH blobs for your iPhone and then upload them later using RedSnow.