Google search is a powerful tool.
RGB and hex are both value formats assigned to describe specific colors in the spectrum; generally speaking, websites rely on hexadecimal while graphic designers deal in RGB, but crossover use is common meaning the new tool should be useful for everyone.
You can pull up the color picker tool with a simple Google search for "RGB to hex." From there, you can either input an exact hex or RGB value to convert or just drag the small circle around the palette to explore.
The "Show Color Values" arrow on the bottom also expands to reveal detailed information about HSV, HSL and CMYK conversions.