Andela is developing a corps of high-quality technology talent across the African continent that will drive the current and future phases of tech-enabled growth around the world. Andela connects companies with top technical talent. They identify high-potential developers on the African continent, shape them into world-class technical leaders, and pair them with companies as full-time, distributed team members. From Udacity to Microsoft, companies at all stages have partnered with Andela to accelerate their product roadmaps while minimizing time spent interviewing, on-boarding, and training new hires.
visit this link for more info http://doubleasam.org/blog/tech/andela-internship-programme-2016-lagos-nigeria

What should the cover letter be about pls

Basically, it should be addressed to Andela and you should state the reasons why you should be considered for the internship.

please do they pay their interns?

The internship position is no longer open, looks like it's now closed.