I suggest you use a Portland cement-based sealer first even though the walls are above ground. This will give the Primer and Paint something real to adhere to. This is a thick and heavy sealer. Measure the area you want to seal and paint and bring the infor w/you to a Paint Retailer. (THey're found in the Yellow Pages under Paint Retailers. I suggest you stay away from the Home Centers which, IMHO relatively-speaking, have a lesser quality product than the Retailers.)
Then, you can use something like Benjamin Moore's Fresh Start Primer to prime the wall. After which you can use their Silicone Acrylic top coat paint. Other Retailers are Sherwin Williams, Finneran & Haley, and MAB just to name a few. My best to ya and hope this helps.