Refresh my memory on creative mode

F4 enables the default mode (you you can access your inventory and use your items), F5 enables the terrain tools (change them by pressing 1-5, and change the materials with your mouse wheel), F6 activates the placement mode (press 1 for vegetation placement and 2 for block placement, then press i to select a plant or block texture), and F7 enables the removal tool (press 1 for vegetation removal, 2 for objects, 3 for construction, 4 for block removal, 5 to remove everything).

If you don't see the creative mode toolbar, just go to the settings -> miscellaneous -> scroll down to the "Creative mode settings" and tick the "Show Toolbar" box