After you have checked your design using DRC, you will need to take account of any errors that DRC has found. A DRC report is created in the same folder as the design, and can be viewed on-screen at the end of the DRC check, but the easiest way to work your way through the errors is using the 'Goto' bar.
The Goto bar can be opened from the View menu, Dockable Bars, Goto Bar. From the dropdown list at the top of the bar, choose Error. The error markers are listed in layer or type order (depending on the settings). Clicking on any of these errors will take you to the error location in the design, where you can then work out what needs altering to remove the cause of the error.
As you make the adjustments needed to correct an error (perhaps by moving an item, or adjusting the Spacings), you can if you wish delete the error marker so you can see how far you have got. But remember, deleting an error will not correct the cause of an error, you have to edit the design items themselves and re-run DRC to verify that the error no longer happens.