You can find the Photoshop gradient tool in the tools panel though the exact location may vary as you can customize the tools (please check out our tutorials on how to modify the panel as well as bring in extra features to that panel. It can be applied to the current art board / image and be applied once or multiple times. it comes with a selection of options that can be found on the top control bar / options bar such as setting the style as well as the blending mode and opacity as well as setting it to reverse (so if it is red to green then it will become green to red instead) as well as transparency (if there is no transparency it will make no difference but if it does exist, it will be ignored) as well as dither (which creates a nicer less banded design for you which should be the default any way)
Hold down the shift key to keep the gradient tool constrained to a straight line in linear type and applied at 90 degrees or 0 or 180 degrees etc. Great for creating all kinds of horizontal as well as vertical and diagonal etc designs in seconds.
You can apply the effect in five different styles but there is some variation even there. You can change the style (it was called type a while back) via the options at the top of the application and set it to linear / radial / angle / reflected / diamond. The diamond design can also be used as a square design. You can change style at any point but the previously applied preset will not change. You can only alter the preset that you are about to apply. Each style offers different features such as an origin point, angle of application and length. Find out more about the styles.
Along the top of the options you have the options with all your current presets. You can use any of those with this feature. The panel is also identical to the same panel in the window menu. Click the drop down to display the current presets loaded in your panel and the only ones you can use, click the preset itself to display the editor. You can select any preset from the purples, blues, legacy, etc and once selected, you can apply it on the document or layer or art board or text layer etc. You can also set the blending modes as well as opacity and also reverse, dither and transparency. The editor is a different kettle of fish and please check out our youtube videos about how to add stops, remove stops, move stops, add in transparency, repeat etc
You may find the generated blends are not that great, there maybe issues with the color especially if you are blending the design with colors that are clashing and creating odd artifacts. You may find it easier and more creative to work with the blends in 32bits per channel mode for RGB or CMYK etc as the color range is vastly increased and this can be done via image menu and color modes and setting it to 32bits. Apply your presets using the various blending modes and apply any available effects as well as adjustments and then revert back to standard 8bit and a panel will appear allowing you to modify a vast array of color settings. This means you can create all kinds of unique colorful blends via any of the presets
You can use the gradient tool in RGB but you can also use it just in a single channel, apply the colors etc in red and apply a different preset in the green etc. You can create truly awesome designs by using that very simple feature.
With the latest releases, you can now also add the preset with a method. You can change the method via the control bar at the top of the application. Perceptual, linear and classic. You will have to decide which one you prefer when you add the preset to your work. You can always combine them so you don't need to just use one method.
You will notice that there is a transparency option for the gradient tool, if the preset you add has no transparency stops then checking it will not matter. If you have one that does then the color result will be different. Say you have a white-black preset with the fade on the black then checking the box will result in the fade being applied, Deselecting it will result in just a solid black and white added to the current layer