... 
 using CADImport;
 using CADImport.DWG;
 using CADImport.DXF;
 using CADImport.RasterImage;
 ...
 
         private void Find_block_Click(object sender, EventArgs e)
         {
             //CADImage.CreateImageByExtension detects format by the extension specified in the argument. 
             //The correct class for any supported format will be used automatically. We recommend to
             //create a new drawing object with CADImage.CreateImageByExtension if import from the existed
             //file/stream is required.
             CADImage vDrawing = CADImage.CreateImageByExtension(@"..\..\..\Files\Entities.dxf");
             vDrawing.LoadFromFile(@"..\..\..\Files\Entities.dxf");
 
             string BlockName = "Block1"; //The block name is Block1
             for (int i = 0; i < vDrawing.Converter.Blocks.Count; i++)
                 if (((CADBlock)vDrawing.Converter.Blocks[i]).Name.ToLower() == BlockName.ToLower())
                 { //found
                     MessageBox.Show("Block with name '" + BlockName + "' has found.\nIndex of the block is " + i);
                     break;
                 }
         }					
This language is not supported or no code example is available.