Hi Srdjan,
TestComplete has advanced support for a number of different grid controls. You can find more information on this functionality in the
Working With Grids help topic. The topic contains all information you need to know about how to work with grids from TestComplete.
If information in this topic does not help you to work with your grid control then provide us with more information on the grid used in your application. First of all, let us know in which programming language the application is written and what exactly third-party control is used in it.