Adverse possession is a complex legal concept. You cannot do this without an attorney.
First, you must possess the property for at least 15 years (if the owner is under a disability, the period of time is extended to 25 years). Second, your possession must be actual, exclusive, hostile, open and notorious, accompanied by a claim of title against all other persons. In other words, you have to treat the property as yours, excluding all others. If your use of somebody else's property is by permission of that owner, you can never obtain title by adverse possession. Your possession must be continued for the entire required period of years. Finally, to perfect your claim, you will need to file a lawsuit at the end of the possession period to "quiet title," asking the court to award you title of the property.
As you can see, if you wait the 15 years and file a lawsuit, you may find out that you did not meet one of the requirements for adverse possession, spent a lot of money and time, and still do not own the property. Because adverse possession is such a rare cause of action in Virginia, each case is very fact specific. Contact an experienced real estate litigation attorney to help you.