Afterwards we will remove the drive shafts. You can always hit a screw driver with a hammer to get them loose in case they are locked pretty bad.
The opinions are not the same about the next step. As you have to weld the spider gears some people will take apart the entire differential for easier acces. Others just keep everything in place. If you want to take apart everything, just make sure you remember how you did it so you can rebuild it later on.
Clean the spider gears before you start. There shouldnt be any oil on them before you start.
And now the actual welding. You can do this as well as you want yourself. Some people just weld one side, others weld everything. Just remember that it can only go wrong once.
And this is how it how it should look when its done. Rebuild everything in reverse order and you are good to go.