I am trying to produce a DEM for my dissertation (i'm relatively new to ArcGIS) so that I can conduct hydrological analyses of catchments. I have downloaded LIDAR (.laz 2x2 km) data and have created a las dataset. It is my understanding that I now need to make this into a terrain dataset to analyse the data. I have made a feature dataset and have imported LIDAR ground points into a multipoint feature class. However, I do not know what to do next. I have read that adding breaklines is important and that there is more preprocessing I need to do.I have catchments that are separate to each other so I believe I may need to merge them. I am looking for help as to what processes I need to execute to have a data set upon which I can use the hydrology toolbox to carry out accurate analysis.