You have the possibility to select all tasks or one row, corresponding to a task or resource in your project.
To select a row, place the cursor on the cell id.
In case of Project Viewer for Win PC/Server and Project Plan 365 for Win PC/Server products, you can select all the rows and columns in a sheet. The Select All button appears in the upper-left corner of sheets:
After selecting the entire sheet, use copy and paste options.
In addition, you can use SHIFT key for contiguous selection of rows, or CTRL key for non-contiguous selection of rows.