You can copy/paste items from Excel into your database using Database Editor (DBE).  The Excel file has to be in the exact same layout as the layout in DBE.  The easiest way to get that layout is to copy one item line in DBE and paste it into Excel.  That gives the layout so you can move your data into that layout, and then copy the items and paste into an item line in DBE.  It will probably take some trial and error if you haven't done it before.  Note that you only get items (and phases, you can copy/paste phases also).  You don't get any assemblies, formulas, variables, item tables etc. 

You can copy/paste items from Excel into your database using Database Editor (DBE).  The Excel file has to be in the exact same layout as the layout in DBE.  The easiest way to get that layout is to copy one item line in DBE and paste it into Excel.  That gives the layout so you can move your data into that layout, and then copy the items and paste into an item line in DBE.  It will probably take some trial and error if you haven't done it before.  Note that you only get items (and phases, you can copy/paste phases also).  You don't get any assemblies, formulas, variables, item tables etc. 

You'll also wanna make sure in DBE that you are showing <All Columns> in order to see all the potential/ available information/ and column headings on an item before populating your data into your Excel sheet.  This would include any database level WBS codes you'd like to assign.  This would be 96 columns before any WBS values you have in your system.  And for a sample item you can see the expected values for example TRUE/FALSE and what to do for the date columns.