>>> And I'm supposed to cure this How
Well, it reallt depends on what the cause is.
From the link supplied, you can see that there are many causes of lumps and bumps, and that list is by no means complete. Is the lump new, or always been there? Has it been there, but you'd not noticed it before? Is it getting bigger/smaller/changing in any way? How long have you had the fish? Is your tank properly cycled, regular water changes, adequate biological filtration - important to know as bacterial problems are associated with poor tank maintenance.
You see, you are not really giving us enough information to really make a guess, and without seeing the fish, the quality of the guess you get depends on the information you give.
If I said to you, "I have a lump on the back of my hand, how do I cure it?" consider all the many things that could be and all the possible treatments. Think of all the questions you'd need to ask before you could begin to reduce the possibilities and you'll see our position.