I have calculated weibull parameters namely, shape parameter and scale parameter using five numerical methods: graphical, moment, maximum likelihood, empirical and energy pattern factor methods. Since I need to compare these methods to find out best method, I need to calculate RMSE and R^2 for each method. 
But even if I know the formulas for RMSE and R^2, I am not being able calculate as I am confused and a bit unfamiliar with the terms used in those formulas.
Please refer the following research journal and I want to clearly understand about 'Prediction performance of Weibull distribution model' section of the journal. 
www.ajsc.leena-luna.co.jp/AJSCPDFs/Vol.3(1)/AJSC2014(3.1-08).pdf

My queries regarding 'statistical tests' are:
1. How do you calculate 'frequency of weibull' or sometimes it says 'predicted data' ?
2. To calculate RMSE and R^2, do we use frequency of the data ( observed and predicted) or actual data (e.g wind speed, temperature) ?

I hope you understood my question.
Thank you!