As I see, you are new to the betheme, so please check out our documentation, there you will find a lot of FAQs, How To and whole documetnation of betheme:
1) You have to change the header and turn on the minimalist option.
Please go to the Theme Options > Header & Subheader > Header, then select a different header type, because modern header leave the black strip (header) to insert some image there.
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