DONT LISTEN TO ANYONE HERE! I'm a freshman as well, and I can tell you from experience that at out young age, there is no need to do specific workouts. Just run easy my man, and when I say easy; that means that you can keep a conversation of about 7 words per breath. If you do workouts for 12 weeks straight, say 2x a week; you will get injured. Im the same build as you; small, lightweight. Just run easy, implement hills into your runs, do your strides. If you want you can do like a tempo run 1-2x per week. Also, progression runs are good too, where you make every mile just a tiny bit harder, but not reaching full tempo run pace.
TRUST ME, you will get hurt, don't do workouts over the summer. I've talked to so many runners about this (EX: Aidan Troutner, last year's NXN winner/Henry Wynne, 3:51 miler, etc)
THEY ALL SAY TOO TAKE IT EASY, Max effort when doing tempo runs, and those should be a pace you can race for 50-60min. But, tempo runs are generally only 3-4mi. STAY AT THAT! Keep the summer simple, and have fun with it. Trust me, your XC season will be good if you do this.