Ok Hex
You will need
1 10mm spanner
2 13mm spanners
1 hexkey (should have come with bocks)
You can use adjustable spanners but make sure you tighten them to the nuts properly or you will round the heads off and then you can't get them undone at all
First undo the large nut and bolt that runs through the hoof
Next undo the large nut and bolt on the lowest joint on the spring (the one where the white plastic packers are)
when you withdraw the bolt the washers will fall out have a good look first to see the order they go back in
The whole spring and hoof should now swing away at the bottom and the hoof will come away from the spring
There are two smaller nuts and bolts at the top of the springnow that you can swing the spring away you should be able to get a spanner on both sides with a little bit of effort undo these two and the spring will come away
The last bit is the two small nuts and bolts at the bottom of the spring (holding the bracket on) undo these and the spring should be free
Putting the new spring in is the reverse of the above make sure you tighten all nuts as you go (you should really replace nylock nuts each time you undo them but I find they last 2 or 3 times before they go slack)
Do them one at atime as then you will have the other one to look at if you forget where things go
Above all don't rush take your time and do it right or you'll regret it when something breaks loose at speed
If you need any more help just ask