I'm a little unclear as to what your question is, are you just trying to make a particular tab in a tab group active? If so, you can open up the section that contains the tab group and select the tab you want to make active and then save the section. Making the tab active in the section will make it active at runtime.
Another option is to use the "active when" feature. Open the property panel for the tab you would like to make active, you should see a field to enter an "active when" condition. If you enter a condition here, and at runtime the condition evaluates to true, then that tab will be made active at runtime.