Yes, you need to have på between tittar and the object you're looking at, much like look at in English. You can use it without på if it is followed by an adverb instead of an object. titta här - look here.
In english is always look at ? Or is used look to ? Like, look to me or it is always look at me ?
Usually look to is used with a general direction, where you expect to see something important. "Look to the north", "look to the sky" etc. It's like "look towards..."
Look at is used for a specific object, the actual thing the person wants you to see.
Sometimes people say "look to something" when they mean "this thing is the source of something". So you can look to someone for inspiration, or look to a book for answers. It really means "if you're looking for something, this is where you can find it "