I really appreciates your feedback for my images.I don't know How to use HDRI Lights in backgrounds. Can you please guide me or suggest me some tutorials? I will try to learn it and will apply in my renders.
It's very easy, actually, once you go past the "but there are no lights loaded" first instinctive objection.
HDRI, that stands for "High Dynamic Range Image" are images, that load the entire range of lightness, from absolute zero (pitch black) to 100% luminosity (pure white). Unlike regular image formats, HDR goes beyond the industry standards on HSL values, making them not only a great creative way to produce real-like skies, but have them illuminate the scenery, on the exact same way the sky does in real life.
Applied to the "dome", their brightest region (there's almost always at least one very bright area on each HDRI image, for this very purpose) will act like the environmental light source. If it's an outdoors HDRI, that means "sun" or "moon", with the blue sky complimenting that light source for more even lighting overall.
There is one default HDRI image preloaded in DAZ, a very blurry outdoors HDRI, that will illuminate your scene, even with no lights included. Here's a fast example for this.
Wether you'd believe this, or not, there was no single light loaded for this, not even a camera, just rendered a quick, low settings V7, with a base pose, and some fast rendering hair. All light, and the shadows included was made from the default pre-built HDRI dome DAZ came with.
Now, the good news are, there are tons of free HDRI images to find online, or even full lighting sets, that combine HDRI with spot, pin, and omni lights, for DAZ.
One thing to know, if you'd use an HDRI only as a light source, and not as a lightsource AND background, is that you can rotate the dome, and move the light angle around to fit your needs.