How do I control seborrah in my scalp

Using head and shoulders shampoo a few times a week works for me.

There are several types of dandruff shampoo that you can try, see here (http://www.dandruffinfo.com/anti-dandruff-shampoos) for an overview. There are also a lot of natural homemade remedies you can try, like soaking your hair in apple cider vinegar. I would just keep trying different stuff until you find what works for you.

Aloe vera gel or shampoo is good for curing dandruff permanently. This is often sufficient by itself.
Using a hair conditioner after shampooing your hair will slow down formation of dandruff, too.