Acquiring land through 'Prescription' is very complex and you would be well advised to seek the assistance of a solicitor, and better still, one who specialises in Conveyancing. I can give you some initial help though.
In Scotland all land is owned - there is no such thing as ownerless land. That said, it is possible to acquire land that has apparently been abandoned by the owner. This seems to be what you wish to do. How do you go about doing that?
Well, quite bizarrely, you need to get a friend or spouse to engage with you in a lie/falsehood/charade (but quite legally) where your friend pretends that they are the rightful owner to the plot you wish to acquire and grants you a gratuitous disposition, transferring to you the plot of land in question. This type of disposition is called a 'a non domino disposition'.
You then need to have that disposition recorded in the land register by Registers of Scotland.
Thereafter you must be in possession of that plot. If you remain the possessor of that plot for a period of 10 years continuously, without any judicial interruption (e'g a sequestration or inhibition), and have done so peaceably and openly, your registered title is safe from being challenged, and good title is then acquired. (Prescription and Limitation (Scotland) Act 1973.
That's the very basics of what you need to know. You would need to use a solicitor anyway so he/she will be able to advise you fully.