Learning white magic can be as easy or as hard as you wish to make it. It is considered to be the good or positive side of magic, where black is considered the bad or negative side. The main thing you have to remember with any of this is that you have to believe in it for it to work. You can't just say the words or do a spell if you can't believe in it. Otherwise it either won't work or could cause negative effects, especially if you are distracted at the same time.
The first thing you need to do is pick up a book that can introduce you to the tools used in magic. Wicca: A Guide for the Solitary Practitioner by Scott Cunningham is a good starting point for learning the basic things you will need to know for performing a spell, along with the different items and how they work. To Ride a Silver Broomstick: New Generation Witchcraft by Silver RavenWolf is another good guide for this.
The next thing is that whenever writing up a spell, that you visualize what you wish to happen. The words, when writing, will naturally cause the effect that you want. Always remember: whatever you put out, can come back to you times 3. So the more good, the better. In the end, everything will balance itself out.
The next thing you should do is what is called a grounding. You basically stand or sit on the ground or floor, or as close to it as you can get. Then you close your eyes and imagine all of the negative energy going out of your body and in to the ground. As that is leaving your body, you want to imagine positive white light filling you completely. This will help you control the positive effect of the magic as well.
One last thing is that before doing any kind of magic, you should take the time to meditate and get into the right mindset. Clearing your thoughts away - you need to let go of the day, the week, or however long you want to go back. Have a clear head as you begin. This will always bring more positive, or white, energy into and around you.
Finally, when you perform the spell, it will be in a good way as long as the intent of it is not to harm another person or thing. Harm is always considered negative. You want to ground yourself once more after performing the spell to release any excess energy that may have built up in your body during the ritual.
One more important note: Meditating every day can only help you will all aspects of your life.