How to change the background?

General
1

Hi, if anyone can help me, when I try to change the background that appears in an interface, it tells me it’s in bitmap format, and what I want to know is how I should change its image.
(Sorry if this bothers anyone, I’m new.)

2

Please post in English

Translation:
Hi, if anyone can help me, when I try to change the background that appears in an interface, it tells me it’s in bitmap format, and what I want to know is how I should change its image.
(Sorry if this bothers anyone, I’m new.)