Sex and Jealousy

I lost my virginity to my boyfriend and around New Years...and...to say the least...it sucked. It was consensual however, and each time we’ve done it since has also just been terrible. One of my best friends is also in a relationship and she always tells me how amazing their sexual acts have been and how good he makes her feel and I’m just so jealous. How do I make my relationship better? How do I become less jealous of hers?