If you want to do it manually you could just try File>Get External Data... and you should be able to import from Excel.
It should also give you choice to import to a new table or to an existing one.
If the fields/columns in Excel match with those of the existing table then there should be no problem importing to it.
If they don't match, there's a problem when you try it or you don't just want to append the data straight away you can import to a new table.
You could then add the data using an append query which isn't too hard.
Just create a new query, add the imported table, goto the Query menu and select Append.
Then choose the table to add the data to and set the fields accordingly.
If you need further help/explanantion post back.
Some of the above is from memory and the menus etc might be different depending on your version of Access. eg in Access 2010 you goto the External Data tab.