Adding sponsor logos or banner ads is easy to do. Logos or banners are treated like images in your app - just upload the final image and place it on your page layout.
For banner ads, you need to consider sizing - 1024px should be the maximum width of your banner ad, to ensure they look good on tablet devices. The height depends on how much visual impact you would like the ad to have in regards to how much space they take up on the screen. This screenshot shows different approaches with heights of 420px, 235px, 170px, and 120px.
If it's an ad, you don't want it to dominate the page too much, so something in the 235-120px range for the height should do the trick. A good compromise is about 170px, as seen below.
For logos, try using a transparent PNG file if available. In the sample below we have used a transparent PNG logo and added "Sponsored By" text using Photoshop - it is one file. If you don't have Photoshop, you can always add your logo to the page layout, then add a text element to your layout that says "Sponsored By". You can also create an external link from the logo to the sponsor's website.
Sponsorship logos can be added to your home screen or to various pages in your app to offer more sponsorship opportunities.