What we recommend is this. Using some sort of graphics program (such as Paint, Photoshop, etc.) create a empty rectangle that is about 1.5" high and 8" wide. Inside that rectangle put your Logo, Address, contact info, etc. Save that as a JPG or PNG and email it to your device. Then in the email, tap and hold on the attachment and then do Copy. Next launch Time Master and go to Setup -> Invoicing -> Companies -> (select your company) -> Export Settings -> Header and then set Mode to Image and in the Image box, double tap to bring up Paste and Paste in your graphic. Then Done, Done and Save.
You can put text in the the bottom box by using the Terms. Create a Terms item that has the text in it that you want. Set that Terms item in the Client record and whenever you create a new Invoice, it will automatically select that Terms and fill in the text.