Hi Everisto, Thanks for contacting CTB. Take a look at our Chapter on Building a Social Marketing campaign (under the Table of Contents graphic), but expect that you will need to adapt some of our suggestions to work better in the culture(s) present in Malawi. Also, click on Toolkits under the Table of Contents and you will find a related toolkit.
Consider doing one or more surveys of high school students to learn what information they most want and need when making decisions about college.
You might also ask some of the NGOs at work there for advice on marketing. You have picked an important issue, and we wish you solid success!