Once you have chosen a model, you need to apply it to your data and generate your forecasts. The steps involved in applying a model may differ depending on the type of model, but usually include data preparation, model estimation, model evaluation, and model forecasting. Data preparation involves collecting, cleaning, and transforming the data to make it suitable for the model. This could involve dealing with missing values, outliers, or non-stationarity, as well as scaling, normalizing, or differencing the data. The model estimation step requires finding the optimal values of the coefficients, weights, or hyperparameters of the model through optimization methods such as gradient descent, genetic algorithms, or grid search. Additionally, validity and stability must be checked using tests such as autocorrelation test, heteroskedasticity test, or stationarity test. Model evaluation involves comparing the predicted values with the actual values using metrics such as MAE, RMSE or R-squared. Model forecasting requires extrapolating trends, patterns or factors of the model through methods like rolling window, expanding window or dynamic window. Confidence intervals or error bounds must also be provided for forecasts through bootstrap, Monte Carlo simulation or Bayesian inference.