@picakhu: Voting up answers to your questions is in general a good thing, and I encourage you to do it. There are several reasons why a person should vote:
- Express gratitude. Voting up an answer is a way of saying: "thank you, I've learned something useful". This does not just apply to answers to your questions! If you read a different thread and learned something you didn't know, voting up the question and/or answer is a way of showing appreciation for the questioner and/or answerer from bringing up an interesting bit of knowledge.
- Help the site function. By voting up or down questions and answers you help the website in presenting the material. The StackExchange platform is community driven, and a user's reputation, which is usually earned through such up/down votes (though occasionally through bounties) is often used as a proxy indicator of how much useful content the user has contributed (whether this interpretation of the reputation score is appropriate is up for debate, but you can't deny this is how many people read it). By voting on things you can use it to encourage and discourage certain content (things that are very suitable/completely unsuitable for this website) or presentation (nicely written exposition/rudely asked question) and make the site better.
- Developing rapport and attracting answers to your future questions. By voting up answers you are saying that you've read through the answer and have found it useful. Most of us participate in this website out of a sense of goodwill. The simple action of a mouse click serves to let people know that when they answer your question, someone will benefit. On the flipside, if you consistently not perform any voting, some users (such as Douglas in the current situation) will naturally start wondering whether the time he has spent was of use to anyone at all!
With that said, how you choose to use the site is up to you. But note that Douglas is most likely not alone in his opinion. (And if you really care about how other people use the site, click through the profiles of the top 30 users of this website. There are people who vote way more than they ask/answer, and there are people who vote way less. They are all well-respected members of the community, so there isn't any hard rules on this matter.)