I received information via the Internet about exercises that will help lengthen my penis. The exercises require one to touch his penis to cause semi or full erection for one hour or more. I want to use these techniques for their intended purpose and not for masturbation. I am overly concerned about the relatively small size of my organ and I would like to enlarge it. Please advise me.

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Lengthening the penis should not be a matter that keeps you busy as long as you can perform the intercourse in the right way and you can impregnate your wife for children.
In fact, the Muslim should fill his time with what is constructive in his religion, his family and his environment. He should study to acquire good knowledge that could help him in this life and the Hereafter. In fact, man is the vicegerent of Allah on earth to establish justice on it, construct on it and worship his Creator Allah on it.
So, we advise you to give up this matter, most of all it could cause you, to commit sins like ejaculating while doing such exercises.
On the other hand, we do not know what you mean by "these exercises need someone to touch the penis". If that person is your wife, it is lawful. If it is yourself, then it may lead to masturbation which is forbidden. If it is an alien person, it is categorically forbidden for you to engage in such a practice.
Allah knows best.