Incubating dreams, always a nice subject! 
Start off by telling yourself that tonight you’re going to dream about this or that. Start with simple dreams, please, don’t make it too elaborate when beggining.
So tell yourself “I’m going to dream about my brother” ( 
T!), “I’m going to dream about nature”, “I’m going to have a dream about family”.
Keep telling yourself that before going to bed—not as a command, but as a wish (you have to remember two things: one, you’re not the ruler of your SC, so don’t go bossing at it; two, you’re also not a slave of it, so don’t just act like one—the quirk with dreaming is always to play with your sobconscious rather than against it).
The first results are not exactly what you expected, but you can see there already were results. Keep asking for a week, always telling yourself how it could be better: “Last night I wanted to dream about the jungle and dreamt about a tree; maybe I could dream about more trees…”
In less than a week, if your recall is good, you’ll start to notice you’re getting skilled at that incubation, so you can try another—maybe in a new level of complexity. So this time, instead of asking for a simple “jungle” dream, ask your subconscious before going to bed “what’s freedom?” or tell yourself to dream about something abstract—eg, ask for a “forum” dream, and see if you can incubae a concrete version of this forum in your dream.
As you get skilled (or: as your SC gets used to you bragging for specific dreams all the time 
), you can start going more and more specific in your dream incubations.
Some people like to wish, some people like to meditate on the subject (and bring the meditation back when they go to bed), some people like to visualize (although I think it’s a poor resource, you can give it a try, those things work differently for each person).
Good luck! 
Any doubt, you can drop me a PM or add me to MSN, ok? 