Hi Everyone!

I'm relatively new to STATA and statistics, so I thought I would come to this forum for some help.

I'm working with data that relates different factors to the returns on schooling. Some of these factors include race, number of siblings, IQ, birthdate, location, years of work experience, years of schooling, etc.

I need to plot the total returns to experience and calculate when it is maximized.
My data set has two variables for experience:
experience and experiencesquared

Should I use one variable instead of the other? How would I go about plotting the total returns and calculating when it is maximized?

PS. If anyone knows how to conduct a test of the overall significance of a regression, please let me know!

Thank you for your help and please let me know if there is any other information I should provide