This is quite a complex war and according to Wikipedia its not over yet. This should take you to the fall of Bangui. What happened after that was mainly political and small scale but it appears that small pockets of fighting continued across the country and there is still fighting today. However, this scenario should take you from the start on 10 December 2012 to the fall of Bangui on 18 March 2013. The timescale is not ideal and so each turn is not an exact timescale but you should get a reasonable sense for the strategic flow. I wont go into deatil of what order the rebels took the towns in but it starts with the capture of NDele, Ouandja and Ouadda. From there the player can advance as they like towards Bangui. the principle consideration is that at each stage they are essentially challenging the governemnt to various agreements for power sharing.
In particular, on 11 January 2013 a ceasefire was agreed and conditions also agreed regarding political affairs but it was broken on 23 January 2013 after which the rebels, who appear to have almost moved back from the capital again moved on to it and between 18-23 March 2013 captured it.