Trendline and given Equation

Without knowing what the data look like, it is hard to give specific advice. Please provide at least a small subset of your data in a format that is convenient for copying, not an image of the data. There is some advice here

about providing data. If you get tangled up doing that (being new to R), at least type out a few rows of data separated by commas and with no spaces. Then describe what you want to graph and the kind of fit you want to do, e.g. linear fit. With that information, some one can easily help you.