See the discussion in the grid's User Guide on deriving Cell Controls.
http://www2.syncfusion.com/ug_latest/gridwin/default.htmlIt is under the Basic Concepts section.
You can also see many examples of custom cells in samples we ship. Look in this folder (or whereever you installed the samples).
C:\Users\YourUserName\Documents\Syncfusion\EssentialStudio\5.2.0.25\Windows\Grid.Windows\Samples\2.0\CustomCellTypes