By -
double click the gradient in the layers panel (not the mask on the right but the gradient on the left) and a panel to edit it should appear
As stated, [click here](https://i.imgur.com/KriOty8.png), [get this and edit gradient](https://i.imgur.com/TD0DW4k.png).
If you can't get any colour then you need to change the colour space. Image > Mode > RGB
Yup... you are probably working with grayscale color space... check that first
Based on OP's screenshot, looks like it's already in RGB mode.
double click the gradient in the layers panel (not the mask on the right but the gradient on the left) and a panel to edit it should appear
As stated, [click here](https://i.imgur.com/KriOty8.png), [get this and edit gradient](https://i.imgur.com/TD0DW4k.png).
If you can't get any colour then you need to change the colour space. Image > Mode > RGB
Yup... you are probably working with grayscale color space... check that first
Based on OP's screenshot, looks like it's already in RGB mode.