I'm not sure you should try to fiddle with this one......This fix can become a little complex, however, if you feel you are competent, first get a manual. If the leak is from the steering box, the seals can be changed but you will need a seal puller, otherwise you could damage the casing which could lead to worse oil leaks once you have changed over the seals. You will need to replace all the rubber seals even if they still look good.
Not sue how many miles and the internal condition of the steering gears, but you might consider buying a rebuild instead of trying to do a reseal.
Look at Atlantic British or Rovers North for their prices.