How can I remove the white background of an image?
There's multiple ways to do this! One way involves going to the top menu 'Select' then 'Color Range'. A window will pop up with a black/white preview of your image with an eyedropper icon to select the pixel color and range. Sliders are available to adjust your pixel selection. Another approach is using the 'Magic Wand' tool and adjusting the 'Tolerance' at the top based on the amount of pixels you want to select (the lower the value the more precise the pixel color selection). The last method is to select the 'fx' icon from the 'Layers' panel for that layer and choosing 'Blending Options'. In the window that pops up, grab the scrubber icon in the 'This Layer' color gradient near the bottom, and begin sliding it to the left. Make sure the 'Preview' box is selected and watch as your white pixels disappear as your slide the scrubber.
How can I create automatic page numbers for all the pages I use in my document?
Go to the 'Pages' panel on the right hand side of your work space, if it's not there go to the menu at the top and choose 'Window' then scroll down and select 'Pages'. Select your 'A- Master' page. Once you are in the master page setup, use the Type Tool (T) to make a text box for where you want to place your page numbers. Select inside your text box and go to the top menu 'Type', scroll down to 'Insert Special Character', 'Markers', 'Current Page Number'. This will create a placeholder number box. Once you go back to your document pages, you will see the text box containing the correct page number. Every new page you create will be updated with the current page number. You can always go back to the master page panel and move or edit your page number text box.
How can I merge two different shapes with different colors with 10 different iterations between them?
Select your two shapes, then go to the top menu 'Object', then scroll down to 'Blend' and select 'Blend Options' from the extended menu. From there, select 'Specified Steps' from the 'Spacing' drop down menu and choose 10 for your step size. Once you have done that, go back to the 'Blend' tap and select 'Make'. The blending of these objects can be explored even further by changing the opacity of one shape or even moving it to another location.