My end of my penis touched a public toilet seat at a bus station. i'm not sure if was there blood. will i get aids or any other std's?

Highly unlikely: Despite the conventional wisdom about public toilets, someone with intact skin and in normal health should not acquire an infection from passing contact. That being said I would not try to test this concept intentionally. If accidental contact occurs, washing then and there with soap and plenty of water is the best mode of action.