I have created this effect in illustrator and then export the image. (72dpi)
By @Fahad35866454w4n8
You should then upload this as an Illustrator picture, and Adobe will create the JPEG for users not having access to Illustrator.
Your 72dpi indication is irrelevant. What is important with pixel images is the resolution in pixels. You can set the ppi value to anything you want, without modifying the image. Indeed, that value is only used during print to check the print resolution and if the asset prints correctly. In that case, the real ppi value will be taken, which is a function of the print size in inches and the number of pixels.
Software, like InDesign, however, use the ppi value to generate the previews. A low ppi value generates considerable previews, which is not what you want.