I find him to be extremely selfish

My husband and I have been married for two years, and there is nothing wrong with our relationship except for his behaviour. I think he is a selfish person who always puts his own needs before my own. He doesn’t do this on purpose, and I believe it’s just because of the way he was brought up. He was an only child and still has that habit of assuming his wants are the most important. I have tried to get him to change but he doesn’t see things from my perspective. I want him to improve this aspect of his personality because it’s not healthy for me or for our future together. What should I do?
You have to simply keep reiterating your message because a lot of what he has been trained to take for granted needs to be unlearned. It may take him a while to undo this, so I suggest you keep that in mind and try being patient. Your relationship will take time to evolve, as you both get a better understanding of each other’s needs. You have a specific approach to this because your background was presumably different. If he cares about you and loves you, this can be resolved in time.

I have been in a relationship with a guy for six months, and he has a very dismissive attitude towards my friends, as if they are just not important enough. I don’t like it because I am always respectful towards the people he introduces me to. Is this a sign that he doesn’t take me seriously, or that he thinks he is superior to me in some way?
It is certainly a sign of disrespect and needs to be called out because it’s not okay. He can have an opinion about your friends because he’s entitled to one, but being dismissive or disrespectful for no apparent reason is not a nice thing. Tell him why this is a problem and, if things don’t change, it’s obvious this relationship needs working on.