Is what the questioner did correct: washing his penis, wetting his hand, and wiping the yellow color on his clothes, then repeating ablution, after feeling a yellow discharge from his penis?

The liquid referred to is most likely urine, which is impure (najis). It must be washed with water until its trace is removed. Wiping it with a wet hand is not sufficient. The proof for this is the Prophet's (peace and blessings be upon him) saying concerning menstrual blood: "She should rub it off, then scratch it with water, then sprinkle water over it, then pray in it."