Though the natural karakas (significator) of a husband and wife is Jupiter and Venus, the DaraKaraka is specific to you. Every man will want qualities of Venus in his wife, but his DaraKaraka will show the other, more individualistic qualities he seeks. Likewise, Jupiter represents the qualities of a good husband (knowledge, forgiveness, virtue, honesty, etc) but the DaraKaraka shows the unique nature of your husband.
How to find your DaraKaraka
The DaraKaraka is the planet in your chart that holds the lowest degree in its sign. When you calculate a birth chart, each planet has a degree number next to it. Identify which one holds the lowest degree and that planet is your DaraKaraka. This should be very easy, but if you have questions feel free to ask.
The house and sign your DK is placed in shows the kind of person your spouse is and your satisfaction with them. For example, my DaraKaraka is the Moon in the sign of Scorpio, and it’s in the 12th house. My husband is a Cancer (ruled by Moon) but his moon is also in Scorpio, and his Sun and Lagna lord are in the 12th house. All kinds of techniques can be applied to this planet to judge whether they are a source of frustration or more of a benefit to your life.
Over the next week I will give a more thorough explanation of what each planet means as DaraKaraka.