You need to be able to lift the front of the tractor in a way where nothing is going to be in the way. I hoist is generally best to use because you will be working on the front end and jack is going to be in the way. Lift the front of the tractor and use jack stands to secure it.
Then remove both spindles from the axle. Look up under the tractor towards the center of the axle and you will see 3 bolts. The center bolt goes through the axle, but all 3 have to come out. When all 3 are removed the axle will drop out (or can be pulled out). In the center of the axle there is a hole for the bolt, pay attention to the 2 bushings that go into that hole as you have to have them there when you put the new axle in place.
That's really about all there is to it. To read it and type it out, it sounds much easier than it actually is. As long as you take your time you should be fine to get this done.