How to: Create new slide on an open presentation.
Solution:
From 'Slide' view, select 'New Slide...' from the 'Insert' menu. Select the layout from 'Choose an AutoLayout' group.
1) From 'Slide' view, select the 'Insert' menu and select 'New Slide...'. (The 'New Slide' dialog box appears.)
2) Select the desired layout for the new slide from the 'Choose an AutoLayout' group.
select layout
NOTE: A highlighted selection box appears around a layout when it is selected.
3) Click 'OK'.
NOTE: To add a new slide with the same layout as the current slide, press and hold down SHIFT, select the 'Insert' menu and select 'New Slide...'.