Should be able to get a leather repair paint. When you get the paint you need to dab the paint on with a small sponge in small amounts , once you have dabbed on the first layer use a hairdryer to dry the paint then repeat until the area is covered. As long as you dont put too much of the paint on in one go and layer you be ok.
Also remember to clean the area first to remove any dirt.
If you know the colour and make of settee you should be ok also you could ask the place you brought it to give you the number of the makers. Dont try to use anything other than leather paint as you will get a poor finish and it wont last as long spend a little more and get the right tools for the job and it will last you a lifetime.
Baby wipes are a good and cheaper way to clean the sofa as well.
Hope this helps.