xgboost regression hyperparameter optimization

thanks for givin advice ı m trying it and how can ı change n-estiminator in XGBoost Tree Ensemle Learner (regression) ?

hi ı have a questions

ı want to chance learning rate and ı want to calcuate only 0.1, 0.5, 0.01, 0.05 and 1 for eta parameter, so what should ı do